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.