1942: Biology

Dr. H. A. Allard of the Bureau of Plant Industry, U. S. Department of Agriculture, reports that a portion of the original tobacco mosaic virus extracted in 1914 was found to retain its infectivity for at least twenty-eight years in vitro under certain conditions. This virus was found, upon testing, to be only slightly acid. The author suggests that this is the reason for its highly infectious nature. Other samples of virus preserved the same way have become entirely innocuous and these were found to have become highly acid in their reaction thus resulting, he claims, in the loss in infectivity.

Dr. Folke Johnson, Department of Botany, Ohio State University, has investigated the resistance of wheat mosaic virus Marmor tritici H. in the soil to heat. He has very carefully controlled his experiments and has found that wheat plants grown in virus-infested soil heated at 40° and 50° C. were affected with mosaic, while all plants in all series heated above this temperature remained healthy. This indicates that this wheat mosaic virus is inactivated in the soil between 50° and 60° C., at an exposure of ten minutes.

Drs. T. P. Dykstra and H. G. Du Buy of the Bureau of Plant Industry, U. S. Department of Agriculture and the University of Maryland, have carried out a series of experiments in an attempt to devise some method of treating plant virus so that their virulence could be retained for a considerable length of time. Their experiments indicate that oxidation had an indirect effect upon the destruction of the virus. Additional information on this problem is still in progress.

It has been known for some time that certain bacteria can be killed by substances secreted by other bacteria but Dr. W. N. Takahashi, of the University of California, is probably the first investigator to show that a substance exists in yeast which destroys the toxicity of a plant-mosaic virus. Chemical analysis of this new virus inhibitor has not been thoroughly investigated but indications are that it may possibly be a polysaccharide or complex sugar.

Dr. Harry Plotz and Reginald Reagan of the Army Medical School, Washington, D. C., are the first to cultivate directly in vitro the street virus of rabies. Two strains were developed, one directly from the brain of a human case of rabies and the other from the brain of a rabid dog. A new method of culture was employed and experiments are now under way to determine whether these cultures can be employed as a vaccine.

Dr. George L. McNew of the New York State Agricultural Experiment Station reports that a new chemical, tetrachloro-parabenzoquinone, has been developed which combats a disease-causing fungus affecting fresh sown peas. While this synthetic chemical is stated to be the first strictly organic, nonmetallic compound to show considerable promise as a plant protectant against fungus diseases, it is also of interest to find, by experiments, that it acts as a good growth-and-yield stimulant as well.

Pyridoxine (vitamin B₆) has been found to be necessary for the growth of cultures of Graphium ulmi, the organism which causes Dutch elm disease as reported by investigators at the Osborn Botanical Laboratory of Yale University. This is one of the few cases where it has been shown that an accessory growth factor is necessary for the life of a parasitic fungus. In this instance the discovery may be of use to phytopathologists in the attempt to control the Dutch elm disease.

Dr. D. G. Langham of the Instituto Experimental De Agricultura y Cria, El Valle, Caracas, Venezuela, reports that the sesame plant or Sesamum indicum, a plant which has been cultivated since ancient times for the high quality of oil in its seeds, has been so modified by experimental developmental procedures that new strains have been developed which have fifty per cent larger seeds without any reduction in the number of seeds found in the ancestral varieties. The standard strains were treated with Colchicine to bring about these changes. To date, no field tests of the comparative seed yields or the per cent of oil of the various strains have been completed.

Dr. H. J. Humm of the Duke University Marine Laboratory, Beaufort, North Carolina, reports that a systematic test of all the more common larger species of red algae of the Atlantic coast from Beaufort to the Florida Keys is being undertaken with the purpose of finding a suitable substitute for agar. This substance is used in bacteriology, medicine, and in certain industries, and it is of utmost importance that a substitute be found to replace the lost Japanese import source of agar. To date several red algae species have been found to yield fairly large quantities of agar.

Dr. H. S. Burr of the Anatomy Department of Yale University has previously measured electrical potentials in animals. These experiments have recently been tried on growing corn plants and he has found that the variations in electrical potentials correspond very accurately with changes in the rate of growth and with internal structural developments.

Clinical studies have been continued the past year on a comparatively new synthetic pain-relieving drug known as Demerol. This substance was first developed in Germany but is now being made in the United States and experiments are being conducted to see whether it will serve as a safe substitute for morphine.

Workers at the Radiation Laboratory of the University of California have carried out some interesting studies in cytology during the past year. Heretofore, one of the stages of cell-division known as the resting stages was considered to be one of relative inactivity. However, with the aid of the atom-smashing cyclotron it was found that those cells in the so-called resting stage were damaged considerably more at one period than at other periods of the same stage. This suggests physiological activity rather than inactivity.

Dr. E. F. Gomez, of the U. S. Department of Agriculture, has reported the finding of a substance in plants which is reported to strongly stimulate sexual maturation in female animals. Extracts from freshly cut or frozen young oat and corn plants, when fed to rats, were found to shorten the period previous to sexual maturity by at least eight days. What these plant extracts consist of has not been definitely determined as yet.

Investigators in the biological laboratories of the Catholic University of America have succeeded in modifying the chromosome numbers in cells of certain limited parts of the nervous system of the common fruit-fly by the injection of Colchicine. Heretofore, experiments with Colchicine have produced surprising results in plant breeding and it is possible that similar results may eventually be brought forth in the animal kingdom.

Dr. J. R. Borland of Hofstra College and New York University has accelerated the metamorphosis or transformation process of the tadpole into the frog by feeding substances rich in cyanide compounds and also by feeding dilute solutions of methyl cyanide to these animals.

Dr. R. D. Manwell of the Biology Department, Syracuse University reports that germs of bird malaria and possibly germs of other diseases as well, can be frozen at a temperature of 100° F. below zero, and maintained at that temperature for a period of seven weeks without damages. Rapid thawing is necessary he states, to avoid killing the germs. The above procedure would be of importance in transportation of these germs for experimental tests.

1941: Biology

Plant Life.

Dr. H. P. Traub of the Bureau of Plant Industry has found that solutions of sulfanilamide and its derivatives act like colchicine in hastening evolutionary changes in plants. Investigations are still in progress to determine whether or not these drugs permanently affect the genetic constitution of plants.

Dr. R. F. Dawson of the University of Missouri has carried out some grafting experiments with the tobacco plant in an attempt to localize the nicotine synthetic mechanism. He has shown that tobacco shoots grown as scions upon tomato roots contain only traces of nicotine while tomato shoots grown as scions upon tobacco roots accumulate large quantities of the alkaloid. Hence, he suggests that nicotine is apparently synthesized in appreciable amounts only in the roots of the tobacco plant.

Dr. W. M. Stanley of the Rockefeller Institute for Medical Research has reported that chemicals such as formaldehyde, when attached to various points on the surface of large molecules of the virus causing mosaic disease of tobacco, do not alter the molecules as far as the ability to reproduce is concerned. Furthermore, the basic reactions of the next generations, do not deviate from the normals as the result of this chemical treatment.

Dr. A. Gorbman of the Institute of Experimental Biology, University of California, has identified an Iodine-storing tissue in an animal below the vertebrate series. Since the thyroid of vertebrates is known to store iodine, Dr. Gorbman was interested in seeing whether the endostyle in tunicates was also capable of storing this substance. The endostyle is considered, by most workers, a morphological homologue of the thyroid. By means of radioactive iodine introductions, followed by photographic plate autographs, tissue iodine can be demonstrated. Dr. Gorbman found that the endostyle did not store iodine nor did any other tissue of the tunicate body proper, store iodine. Only the stolonic septum, a reproductive organ contributing to the formation of buds, showed any ability to store iodine.

Animal Experiments.

Dr. P. Doudorouf, of the University of California, has shown by recent experiments that many fish live in the cold ocean water because of necessity rather than choice. In one of his experimental tests, water in a tank varied in temperature from warm to cold, and the fish were allowed to swim about and choose the most desirable temperature. Some fish preferred cool, others warmer water, in accordance to their inherited inclinations, but all of them preferred warmer water than that which occurred in the natural habitats of the fishes.

While the anterior chamber of the eye has been used as a site of transplantation in numerous mammalian experiments, Drs. B. Lucke and H. G. Schlumberge of the University of Pennsylvania medical school are among the first to use this region as a site for transplantation of cancerous tissue in frogs. The cancerous tissue used in these experiments was an adenocarcinoma of the frog, which in structure and behavior resembles the most common kind of cancer in man and animals generally. Their observations of the growth of these transplants led them to conclude that the pattern of cancerous growth was influenced decisively by surface forces and also that, as in normal tissues, the effect of temperature was an acceleration of growth at high temperatures and retardation at lower levels. Hence, cancer growth was shown to be governed by the same physical factors that govern normal growth.

Dr. R. W. Briggs of McGill University, has recently reared tadpoles for various purposes on a diet which included boiled spinach. Of this group, ninety per cent were found to contain numerous kidney stones upon autopsy. However, when the spinach was eliminated from the diet in another group of tadpoles of a similar species, less than three per cent were found to have kidney stones. Spinach has a high oxalic acid content and the explanation for the deposition of crystalline stones in tadpole kidneys is no doubt due to this substance in spinach.

Dr. L. S. Stone of Yale University School of Medicine has developed a technique whereby the eyes of salamanders can be successfully transplanted and the return of vision accomplished. The transplants were made at all ages, from the embryo to the adult and even eyes were exchanged and transplanted between salamanders of different species. It was of interest to note, in these experiments, that the severed ends of the optic nerve did not unite. Instead there was a new growth of nerves and retina and the restoration of vision was accomplished when this process was completed. Thus far eye transplantation experiments in mammals have not been successful in the Yale laboratory.

Physiological Experiments.

Dr. Paul Weiss of the University of Chicago reports that the ends of small nerves that have previously been severed, may again be united by placing them in a cast made from a fragment of an artery. While cut ends of nerves are usually stitched together, it is impossible to do so with very small nerves and the above procedure offers a new successful surgical approach.

Dr. R. F. Sognnaes of the Department of Pathology, University of Rochester School of Medicine, has produced experimental caries in rats by feeding a coarse corn diet for an extended period. Furthermore, he has successfully stopped the caries process and found a regeneration of dentin when the same group of rats were changed to a stock diet which was adequate in every respect. This experimental study offers a better approach to the study of the process of caries disintegration and the reparative processes.

Drs. M. F. Guyer and P. E. Claus of the University of Wisconsin have demonstrated a new method by which the differences between normal and cancer cells can be shown. Cancer cells removed from tumors artificially induced in rats were placed in a centrifuge and by a comparison with normal cells it was found that centrifuging failed to stratify the cancerous cells while the normal cells became arranged into strata or layers. This may indicate that cancerous cells are more viscous than normal cells.

Drs. C. Reich and W. F. Dunning of Lenox Hill Hospital and Columbia University have shown that rats having a high white blood cell count, particularly neutrophile cells, have a longer life span than do those strains of rats having a low average white cell count. Sex differences associated with length of life also corroborate these findings. Females had a higher white count than males and the females in those strains studied had longer life spans.

Dr. S. Gluecksohn-Schoenheimer of Columbia University has developed a new method for cultivating entire early mouse embryos. The embryos were removed and transplanted into 800 hour chick embryos so that they come to lie near the shell, the opening of the shell was then covered with glass so that the future development of the mouse embryo could be observed. These mouse embryos developed up to a stage in life when maternal circulation became essential for the nutrition of the mouse embryo.

Sex Modifications in Mammals.

Dr. C. R. Moore of the University of Chicago has succeeded in artificially modifying the sex of a mammalian animal. Heretofore, sex reversals or modifications by artificial methods were common experiments in birds but not successful in higher forms. The animals used in these experiments were opossums, which are ideal for these experiments because sex differentiation occurs after the animals are born and placed in the mother's brood pouch. The sex modifications were brought about by treatment of the young with male and female gland hormones. See also ENTOMOLOGY; ZOOLOGY.

1940: Biology

Plant Life.

Influence of Oxygen and Growth of Plant Tissue.

That oxygen abundance or lack determines the character of growth masses of plant tissue in a culture medium, has been shown by Dr. Philip White, of the Rockefeller Institute for Medical Research at Princeton, N. J. He found that if these tissues received a sufficient supply of oxygen they would continue to grow but the cells would not differentiate. However, when oxygen starvation was intensified the undifferentiated mass of tissue proceeded to produce small leaves, supported on small stems.

Carbon Dioxide Absorption and Use.

Dr. H. Gaffron of the University of Chicago has reported experiments where one-celled green water plants would absorb carbon dioxide in the dark. Previously, Dr. Gaffron had reported the ability of these plants to combine oxygen and hydrogen, presumably with the release of energy for their own use in dim light. Now in later experiments he finds that if a small amount of carbon dioxide is added to the artificial atmosphere a part of the carbon dioxide will be absorbed by the plant in the absence of light.

Another case of unorthodox use of carbon dioxide was recently reported by Prof. S. O. Mast of Johns Hopkins University. He found that a protozoan or one-celled water organism known specifically as Chilomonas paramecium could manufacture food substances, such as starch and fat, without chlorophyll and in the absence of light. And further than that, he found this organism could produce food and reproduce and grow in a solution containing only inorganic materials. This is probably the first time an organism, which is usually considered in the animal kingdom, has shown the ability to do a plant's work and manufacture food out of the inorganic substances especially without the commonly excepted substance chlorophyll. These two experiments on plant and animal forms will no doubt necessitate a revision of the accepted ideas regarding photosynthesis or the processes of food formation and energy liberation.

Effect of Colchicine on Plant Genetics.

In the field of plant genetics the drug colchicine has been used to carry out more interesting experiments. Drs. H. E. Warmke and A. F. Blakeslee of the Carnegie Institution of Washington have reported profound sex changes in an Old-World species of plant known as Melandrium dioicum when this plant is treated with colchicine. New strains with double the number of chromosomes have been produced. Furthermore, they have produced a strain which has male and female (pollen and seed-producing) parts in the same flowers. This is a profound change since this plant in nature bears male and female flowers on separate plants.

Other possibilities as the result of plant treatment with this drug colchicine have been carried on experimentally by Drs. B. R. and M. R. Nebel at the New York State Agricultural Experiment Station. They have also artificially produced plant cells with increased chromosome numbers and hence, have produced marigolds, snapdragons, and other species of flowering plants which have entirely different genetic properties from those of the original species.

Vitamins in Relation to Plant Growth.

Experiments with vitamins in relation to plant growth have been continued and in the experiments carried out by Dr. R. Denison of the State University of Iowa, two vitamins necessary for human health have been shown to stimulate plant growth. In these experiments it was found that riboflavin, one of the B vitamins, enabled the eggplant to develop longer stems with heavier tops and the leaves were coarser in texture and darker in color than the untreated plants. Vitamin C or ascorbic acid was shown to have caused unusual gains in the size of the tobacco leaf also.

Unicellular Organisms.

Social Behavior in Unicellular Organisms.

Professor H. S. Jennings of the University of California at Los Angeles has made a comprehensive study of the social behavior in unicellular organisms. He has found that the sex drive or the urge to find a mate which is so common and well recognized in higher organisms is found also at the very bottom of the evolutionary scale. This does not mean that the small unicellular organism is as highly developed socially as higher animals, including man. Professor Jennings explains this by stating that the unicellular organism, such as the Paramecium, reacts without any awareness of the action or its relations. Man and higher organisms operate on a social scale wherein the awareness of the action is present and often times consciously planned.

Effect of Nucleus Removal in One-Celled Animal.

Professor Vance Tartar and Dr. Tze-Tuan Chen, in researches conducted at Yale University and the University of California at Los Angeles, have shown that the one-celled animal, Paramecium, can go through characteristic mating reactions even though the nucleus has been removed. This is most remarkable, since the nucleus of a cell has usually been considered as the controlling center for most physiological activities.

Animal Life.

Influence of Environmental Variation on Invertebrate Survival.

Professor D. M. Whitaker of Stanford University has shown that the brine shrimp Artemia, an invertebrate species, has the ability to withstand remarkable environmental variations. He found that this species, when in the embryonic or encysted state, could survive when scaled in a glass tube under vacuum and hence without oxygen for six months at least. Other embryos were able to develop normally after a 24-hour immersion in liquid air, at a temperature of 310 degrees below zero.

Color Changes in Animals.

Professor G. H. Parker of Harvard University states that the common catfish can change its color in much the same manner as the chameleon lizard. However, the only difference seems to be the time required. The catfish changes its colors much more slowly. Doctor Parker has carried out extensive experiments on pigmentation in various forms of animals and more recently has discussed the physiological mechanism of these color changes. In general, he suggests that secretions, as the result of glandular reactions, are probably involved. The pituitary liberates intermedin and the nerves secrete a substance (probably acetylcholine); these two are the substances which darken the skin while the hormone which contracts the pigment and lightens the skin is probably adrenalin from the adrenal glands.

Sex Reversal in Fish.

Drs. F. M. Baldwin and H. S. Goldin of the University of Southern California have performed experiments on sex reversal in fish, changing females into males by the injection of synthetic male sex hormones.

Embryonic Membranes of Fishes.

Dr. C. L. Turner of Northwestern University has described embryonic membranes in several higher species of fish. These species give birth to their young alive instead of laying their eggs in the water. The membranes which surround the embryos prior to birth are different in detailed structure and function but do resemble similar membranes in higher warm-blooded animals.

Method of Cobra Venom Ejection.

Mr. C. M. Bogert of the American Museum of Natural History has carried out some interesting researches to show, on the basis of experimental evidence, that there are several species of cobras that actually throw or eject their venom straight forward from their mouth. Heretofore, it has been thought that the venom elaborated by these snakes was ejected from the mouth by expulsion of air simultaneously with the dropping of venom into the mouth cavity. Hence the name 'Spitting Cobra.' The experiments of Mr. Bogert show that the venom of these species can be forced out of the fangs directly ahead because of the anterior position of the openings of their fangs.

Technique for the Study of Chick Embryos.

The development of chick embryos can be observed and subjected to experimental procedures by means of a modified technique of making windows in the shells during incubation. This technique has recently been perfected by Professor J. W. Price and E. V. Fowler of Ohio State University. Their technique was simply the removal of a portion of the shell in the large end of the egg and the replacement of a larger shell cap over the open end. The eggs could then be placed upright in the incubator and the cap removed from time to time for observation. This technique is much simpler than that reported by the writer and others but no doubt lends itself more easily to bacterial infection.

Colchicine in Genetic Studies in Animals.

The drug colchicine has been of extraordinary value to plant physiologists in producing genetic varieties but this same drug does not lend itself to animal experimentation along hereditary lines with the same degree of success. Drs. H. A. Davenport and F. B. Queen of Northwestern University recently reported experiments attempting to modify the heredity of rats with colchicine. Their chief difficulty seemed to be the high toxicity of this drug to animal tissues as compared to plant tissues. In concentrations high enough to be effective, the drug caused local necrosis of the tissues in the injected area, while in low concentrations no hereditary effect was noted. These workers suggest the most hopeful possibility for the use of this drug in the genetical studies of animals will probably be the injection of low concentrations directly into the sex organs and in this way modify indirectly some of the hereditary characteristics.

Viruses.

Viruses, best known as causing diseases like infantile paralysis and influenza, may some day reveal the secret of the origin of life. Each year more advances are being made in the study of the nature of these substances. This year Drs. G. A. Kausche and Ruska of the Siemens-Halske laboratory in Berlin were able to demonstrate in photographs with the electron microscope the plant virus which attacks the green chlorophyll particles of leaves. See also ENTOMOLOGY; ZOOLOGY.

1939: Biology

Chemicals and Hormones in Plant-Growth.

In the field of plant biology, just as in the field of animal biology, the chemical messengers or hormones have caused new and stimulated interest the past year. Pollen grains were made to germinate faster and larger if they were treated with a growth hormone. Dr. P. F. Smith of the University of Oklahoma has treated these pollen grains with indole-3-acetic acid and has not only cut the germinating time 50 per cent in some three or four species, but has also succeeded in increasing the percentage of germination in at least one species. These results may have their practical value in plant breeding and greenhouse horticulture.

Iodine has long been known to be essential for the normal health and growth of animals, including humans. Now, Dr. W. L. Powers of Oregon State College reports that iodine may prove as essential for plant life. In his carefully controlled experiments he has shown that the amount of iodine needed is only about one part to two to four million parts of water. He suggests that iodine may be necessary for chlorophyll formation. However, he finds that lower forms without chlorophyll, such as the yeasts and also the nitrogen-fixing bacteria of the root nodule, also seem to thrive better with the addition of iodine to the media.

Dr. R. W. Oliver of the Ottawa Central Experimental Farm has carried on some interesting experiments to show that honey is a better growth hormone than some of the commercial phytohormone preparations. The most extensive tests were made on varieties of the chrysanthemum. In addition, he found that evergreen cuttings would also respond to the solution of one part honey and three parts water. It is suggested that some chemical in the honey is responsible for this growth stimulus.

Dr. E. D. McAlister, a biophysicist at the Smithsonian Institution has discovered a chemical which acts as an intermediary for carbon dioxide and chlorophyll. While Dr. McAlister was testing the carbon dioxide utilization of plant seedlings, he found the plants to be using carbon dioxide for a short time after they had been placed in complete darkness. This seemed to be contrary to the established idea of photosynthesis. Hence, Dr. McAlister began a search and demonstrated a chemical which acts as the intermediate substance and seizes the carbon dioxide molecule and delivers it to the green coloring matter or chlorophyll of the plant.

A Chinese biologist, Mr. Cheong-yin Wong, while working at Michigan State College, has shown that by the treatment of the ovaries of unpollinated flowers of some plants with the growth hormone, naphthalene acetic acid, seedless fruits could be produced. Seedless watermelons, cucumbers and green peppers were produced by the above method. Mr. Wong reports that these fruits appeared to be normal in respect to flavor and texture when compared to the seeded varieties.

Dr. F. E. Meier of the Smithsonian Institution has shown that ultra-violet radiation, which is known to be deadly to some cells, is also a stimulant to growth in the same type of cells if the radiation is administered in doses of less than the lethal magnitude. Dr. Meier used cultures of the species of unicellular algae or water plant. The interesting phase of this experiment seemed to be that stimulative influence of radiation was not only present in the treated generation but that the accelerated proliferation was carried over into succeeding generations without the successive generations having been so treated directly.

Experiments in Genetics.

Interesting studies on chromosomes and other structures of importance in the field of genetics have continued. Dr. J. O. Beasley, of the Bureau of Plant Industry, has shown that the drug colchicine when applied to young plants, brings about a doubling of chromosomes in the cells and hence the new plant which is created will breed true and not be sterile as most hybrids are. Dr. Beasley's experiments were carried out with hybrids of several varieties of the cotton plant. Other workers are carrying on similar experiments with this drug on other plants such as tobacco and also with berries and fruit trees.

Another series of experiments, somewhat related to the above have been carried on by Dr. D. Kostoff of the Institute of Genetics in Moscow. Dr. Kostoff has used a fungicide, distributed under the trade name 'Granosan' for doubling the chromosome number in plant cells. He states that this substance has the advantage over colchicine in that seeds treated with it are not subject to fungi infections, whereas the colchicine treated ones may be thus attacked.

Parasites as Purveyors of Nitrogen.

Rust jungi, probably the worst parasitic enemies of wheat and other grains, may possibly be shown to be also beneficial to their host plants. Dr. Branquinho d'Oliveira, of the National Agronomic Station at Lisbon, grew seedlings of wheat on media from which all nitrogen had been eliminated. He then inoculated a portion of this series with spores of various species of rust fungi. An analysis of the plants at a later time showed that those receiving the inoculation had a higher nitrogen content than the control series. These experiments suggest that rust fungi may be able to take nitrogen from the air and fix it just as do some root nodule bacteria in the pea and clover plant family.

Cellular Differentiation.

In the field of embryology an interesting series of experiments on plant tissue have been carried out during 1939. Dr. P. H. White, of the Rockefeller Institute for Medical Research, Princeton, N. J., has developed a technique whereby he can grow plant cells in culture media, and while growth of these cells will continue indefinitely, no apparent differentiation occurs unless the growth conditions are altered. In his experiments, Dr. White has removed unspecialized cells from a wound area of plants such as the tobacco and tomato. He places these unspecialized cells on a culture medium having the necessary mineral salts, carbohydrates, vitamins and hormones, and allows them to grow. Dr. White has been able to keep these cells growing continuously as undifferentiated cells for several years on the culture media used. However, when the unspecialized cells are placed in a nutrient solution instead of a more viscid medium they sink to the bottom and then they differentiate into stems, leaves, roots and so forth. Just why cellular differentiation can be induced by this method is still unanswered.

Vitamins and Other Chemicals in Plant Growth.

In the field of vitamin research, investigations are being continued and new vitamins are being added to the present alphabet. At the same time the chemical structures and the synthesis of old vitamins are being completed. A school of investigators at Harvard University and St. Louis University Medical School, working independently, have recently arrived at the same structural formula for vitamin K. This vitamin has been shown to play an essential rôle in the coagulation of blood. While the investigations leading to the discovery of a blood coagulating substance such as vitamin K have been of extreme importance, the discovery of a chemical in the human body which prevents the coagulation of blood may some day be of equal importance. This new chemical known as aspartic acid has been described by Doctors I. J. Greenblott and M. X. Sullivan of Georgetown University. It is an amino-acid found in both plant and animal tissues. This chemical which is present normally in food and liberated therefrom by the process of digestion may be the anti-coagulant of blood which acts as the weapon against thrombosis. While work on this chemical is only in its initial stages, it is possible to visualize the use of the chemical, after its chemical structure becomes known, as a substitute for sodium citrate and other chemicals now used as anti-coagulants in blood collections outside of the body.

Important investigations on vitamin B have been reported by Dr. R. J. Williams of the University of Oregon. He found that this vitamin stimulated the growth of yeast. Since its discovery this vitamin has been shown to function as a stimulating substance important in the growth of a number of living things from bacteria, fungi, plants and lower and higher animal life. For this reason it is called the universal vitamin or pantothenic acid.

Another substance, given the name coenzyme R has recently been discovered by Doctors F. E. Allison and F. W. Minor of the U. S. Department of Agriculture. This substance is thought to be indispensable for the growth of nitrogen-fixing bacteria which inhabit the roots of clover and related plants. Another nitrogen-fixing bacterium which lives free in the soil instead of the roots proper, has been found to require small traces of a metal called molybdenum. This metal has long been found to be useful in the steel and metal industries but Doctors D. Burk and K. Horner were the first investigators to find it to be necessary for the growth of plants.

From this brief résumé on recent researches on biology it can be seen that the smallest plants, just as the largest animals, require vitamins, hormones and other substances for their successful development, growth and reproduction. Furthermore, it has been shown in a number of instances that the nature of these essential substances are identical in plant and animals. See also HORTICULTURE; ROCKEFELLER FOUNDATION; ZOOLOGY.

1938: Biology

Scientists in the fields of animal and plant biology have continued to contribute outstanding discoveries throughout the past year. In a resume of contributions of the year, it becomes increasingly difficult to mention those which stand out. Contributions which now seem to play a minor part may be the stimulus or, even more, the actual beginning of a new conception in the years to follow.

Interaction of Plant and Animal Life.

One of the most interesting experiments seems to be that demonstrated by Dr. Ralph Buchsbaum, of the University of Chicago. Here we have striking evidence for the close relationship between animal and plant life. Dr. Buchsbaum used chick embryo tissues and mixed with them plant cells (chlorella) commonly found in stagnant water. He found that if this mixed culture was kept warm and under lighted conditions, the chick cells and the plant cells would continue to thrive much better than when either type of cell was cultured alone. This mutual relationship resulted in greener and healthier plant cells, while the animal cells divided more rapidly and did not become senile and die off so quickly.

Disease Viruses.

Although the virus molecules are now fairly well established as non-living things, they are nevertheless found to possess certain very lifelike characteristics. These molecules may not represent the lowest beginnings of what may turn into life; but, conversely, they may represent the last stages in the ultimate degeneration of life. Biologists throughout the country are now working on these virus units in an effort to find out how they synthesize themselves. These protein molecules can invade a cell, take parts of its living material, and then build up additional molecules like themselves. If a few of these are introduced into a plant or an animal, they multiply into millions and make the host sick.

Ever since Dr. Stanley's pioneer work on the tobacco virus and his demonstration of its protein nature, other workers have continued work on this virus with the hope that man and animals would some day be protected against the numerous virus diseases. The smallpox virus particles, hitherto unseen under the highest magnifications of the microscope, have been made visible by means of an improved electron microscope developed by Dr. Franz Krause of Germany. These viruses are very much smaller than bacteria and are rendered visible at something over 2,000 diameters. The virus of other diseases such as encephalitis, infantile paralysis, yellow fever, and parrot fever are likewise being studied in an effort to determine their physical, chemical, and biological characteristics. A new method of inactivating plant-disease viruses by ultra-violet radiation and X-rays has been reported by Dr. N. W. Pirie, of Cambridge University. Irradiation tends to enlarge the crystals that are obtained from the viruses and hinders their infectivity. This discovery may pave the way for a possible future method of vaccinating plants against certain diseases. It may also indicate a way in which safer smallpox vaccine may be prepared.

Synthetic Hormones for Large-scale Farming.

While hormones, or chemical messengers, have continued to yield new and startling results in the animal world, they have also resulted in outstanding contributions in the plant kingdom. Pioneers in plant hormone research were Drs. P. W. Zimmerman and A. E. Hitchcock, of the Boyce Thompson Institute for Plant Research, Yonkers, N. Y. As early as 1935 they demonstrated that some 16 new chemical substances would grow root hairs on plants very rapidly and on numerous parts of the plant itself. They applied these chemicals as solutions in water. At the present time these synthetic chemicals, that grow roots many days before they would otherwise sprout, are ground into a talc or other inert dusts for easier and more effective application. This year these chemicals are being used on a large scale on field trials of actual grain production in various parts of Canada. Wheat on the Western plains may be able to get its roots into the soil more quickly and securely if the seed is first dusted with hormones. This may hence mean the difference between a crop and a failure, for wheat so treated may then withstand wind and drought at an earlier time after seeding.

Roots from Flower Tissues.

Other interesting contributions have also been made in the field of plant biology. In experiments reported by Dr. La Rue, of the University of Michigan, all parts of flowers from certain plants have been induced to form roots. The secret of this feat was the technique for keeping the small and delicate pieces of plant tissue alive and in good condition. These tissues were placed on a sterile nutrient jelly after bacteria and molds had been killed by antiseptic solutions. On this nutrient substance the cells of the flower lived indefinitely and not only sprouted roots but started stems and leaves as well. These experiments show that highly organized cells which make up the flower of the plant are in reality not so fixed or determined in their organization that they cannot be induced to form the cellular components of the leaves, stems, or roots of a plant.

Plant Behavior under Chilling.

It has long been known by gardeners that certain plants have to be nearly frozen each winter so that they will grow normally the following year. Earlier experiments have shown the beneficial effects of chilling on woody plants and seeds. Now, Dr. H. Kurz, of Florida State College for Women, has added considerable new information to the above facts. He has experimented with some twenty kinds of Northern wildflowers and has demonstrated that their rootstocks must be held at temperatures near freezing for several weeks if normal growth and flowering is to take place in the spring. An interesting phase of his experiments was the peculiar behavior shown by four species of plants received from New England. These four species had to be chilled before normal growth and flowering occurred. However, identical species that normally are found in Florida required no chilling for normal growth. Here seems to be an example of physiological adaptation. While there are many Southern plants which find Northern climates too severe, there also appear to be numerous Northern plants which find that Southern climates are not severe enough for the stimulation of normal growth and reproduction.

Chlorophyll, Porphyrins and Photosynthesis.

Chlorophyll, the light-sensitive chemical which enables plants to convert light energy, water, and soil foods into bodily structure may eventually be synthesized. Drs. P. Rothmund, of Antioch College, and A. Menotti, of Ohio State University, describe the creation of chemicals, known as porphyrins, which are extremely light-sensitive. These chemicals were made synthetically by these scientists, but they may also be obtained by extraction methods from the green pigment (chlorophyll) of plants or even the red pigment of blood. When these chemicals are injected into the vascular system of animals, the animals become exceedingly sensitive to light and can carry on their normal activity only in darkness or very dim light. The derivatives of synthetic porphyrins seem to exert greater influence than do the naturally derived porphyrins. This series of studies will no doubt lead to a better understanding of the general problem of photosynthesis.

Mutual Activities among Plants.

Various phases of what may be termed plant sociology have been studied from time to time. Various American and German scientists have shown that the mere presence of odorous plant substances such as apples, turpentine, or oil of bergamot may accelerate seedling growth under light conditions but seems to hinder it under conditions of darkness. A German physician, Dr. G. Madaus, has recently shown by experimental means that corn and wheat planted in the same pot will produce a more rapid growth of the wheat. He also demonstrated that bean seeds in water first used to bathe the roots of oats sprouted more rapidly than did similar seeds in water previously used to bathe corn roots. It is probable that root secretions are responsible for these mutual activities, and this work may lead to the discovery that hormone-like substances are specifically produced and liberated through the roots of plants.

Intercellular Hormones.

A better understanding of the nature of life and cell growth may result from the discovery of substances produced from injured cells, which in turn cause the rapid multiplication and proliferation of healthy cells. These substances are at the present time called intercellular hormones. They are purified out of injured cell extracts. While they have not been completely analyzed chemically, there are indications that they are higher fractions of our well-known proteins. Practical application of these substances has already been put to use in a Cincinnati hospital for the treatment of third degree burns. Burns thus treated seem to heal in a minimum time without the wide areas of scar tissue which usually result from such burns. There are numerous kinds of injured animal and plant cells which have been shown to be capable of yielding this intercellular hormone, and they all cause a rapid growth of a wide variety of healthy cells. It seems of special interest to note that these substances induce proliferation of connective or supporting tissue cells known as fibroblasts. The fibroblasts are the cells which are characteristic of certain types of cancer. Hence a further advance in the knowledge of certain cancerous diseases may also be indirectly recorded.