1938: Zoology

Contributions have been numerous in both general branches of the zoological field, namely experimental and strictly observational. Both branches have yielded reports which deal with countless forms of animal life. In reviewing the advancements of the year, numerous species of animals from high vertebrates or mammals to lower vertebrates and invertebrates must be included.

Effects of Drinking Heavy Water.

Since 1935, when Dr. Urey, of the Chemistry Department, Columbia University, discovered the existence of heavy water (deuterium oxide), scientists have wondered what would happen if one drank this water instead of the ordinary kind. It has been difficult to perform experiments of such a kind until recently, because this substance was not produced on a large enough scale. However, this year Dr. Barbour, of Yale University School of Medicine, has reported a series of experiments where mice were administered variable doses of this heavy water. When mice were kept on only one-fifth saturated heavy water they were not poisoned; instead, their life processes were kept going at a more rapid rate. Chemists have hitherto theorized to the contrary because of the fact that chemical energy of heavy water is low. In these experiments the heavy water seems to stimulate the sympathetic nervous system. The hair of the animals becomes elevated as though they were frightened, and their eyes tend to protrude. Dr. Barbour reports that this effect is produced by the heavy water's reaction in preventing the rapid decomposition of adrenaline, which normally is secreted into the body but which also normally disappears too rapidly for the above effects to be sustained. His experiments demonstrate besides that the mice will survive for only about one week if all their natural drinking water is replaced by heavy water. We see from these experiments that, depending upon the amount of heavy water consumed, life goes on at a more rapid rate, or that even death may ensue if heavy water is used for drinking purposes.

Vitamins.

Vitamins also have been prominent in the field of research the past year. Vitamin E, called the fertility or anti-sterility vitamin because rats need it in order to bear young, has at last been identified chemically, reduced to a chemical formula, and manufactured in the laboratory. The chemical part of this work is reported by six or seven scientists from 3 or 4 institutions in this country. This synthetic Vitamin E, chemically termed alpha tocopherol, when fed to sterile female rats allows them to raise young as if they had never been deprived of the natural source of Vitamin E occurring in numerous kinds of foods. Dr. H. M. Evans discovered Vitamin E some sixteen years ago as the result of numerous nutritional investigations, and he has continued his investigations at the Institute of Experimental Biology at the University of California with this new synthetic Vitamin E, to compare its effect on animals with that of the natural occurring source. He finds the effects of the synthetic substance (alpha tocopherol) identical with those of the natural vitamin. However, he reports that other chemicals have also been obtained which have a Vitamin E-like effect. These results are more or less similar to those obtained with other vitamins where several chemical substances may function similarly; e.g., Vitamins A and D. Another group of scientists, working at the Iowa State College, has reported that this vitamin E, which is so essential for normal reproduction in rats, is apparently not a diet essential for farm animals. They fed mixtures deficient in Vitamin E to goats, rabbits, and sheep and found that these animals would reproduce normally through at least several generations, unhampered by the lack of this vitamin. It is possible that the same effects might be applied to man. At any rate it is quite apparent that the effects of special diets are not invariably the same in rat nutrition as they are in other types of animal nutrition. Here we have another instance where studies on one type of animal cannot always be applied to other animals or to man.

Other new vitamins have been discovered during the past year and, as has been the custom, they are given names from the letters of our alphabet, so that the vitamin alphabet now stretches from A to Z with only a few letters missing. Vitamin T is found in egg yolk and seems to increase blood platelets, which are important for the coagulation of blood. Vitamin P is another new one, which is found in lemon juice and red pepper. Its exact function is not known, but it probably helps the body to retain Vitamin C.

New Hormone.

Another new hormone has been added to our already long list. This hormone has been described by Dr. Collip, of McGill University. It has been called 'the specific metabolic principle' and is produced by the middle portion of the pituitary gland. According to Dr. Collip and his associates, this principle speeds up the rate at which the body converts food, fuel, and energy. It has long been demonstrated that this vital process, known as metabolism, is controlled by the thyroid gland, which receives its stimulus from the pituitary through another hormone known as the thyrotropic hormone. However, this new principle acts independently of the thyroid. This has been demonstrated by injecting the principle into thyroidectomized animals, and noting the increased metabolic rate. Along with the above effects, this hormone also seemed to produce other striking effects, such as neutralizing the effect of insulin and also exercising some control over the adrenal glands.

Electric Eel.

An interesting experiment was carried out by C. W. Coates, of the New York Aquarium, and Dr. R. T. Cox, a physicist, of New York University. They connected an electric eel, which normally inhabits the fresh waters of South America, with a cathode ray oscillograph. When the eel was irritated, it would light a two-watt neon lamp. Furthermore, when connected with outside currents, the eel would send a modifying current through a loud-speaker system, loud enough to be audible. These scientists state that this eel, which is over four feet in length and weighs about ten pounds, is capable of discharging on an open circuit a peak voltage of 500 volts.

Fish Out of Water: Cause of Death.

Dr. A. G. Huntsman, of the University of Toronto, reports that the death of fish out of water is probably due chiefly to their violent struggles rather than to their inability to obtain sufficient oxygen through their gills. In his examinations of the tissues of fish after death, he found these tissues to be low in glycogen, which is a substance known as the energy-yielding principle. He also found a high concentration of lactic acid in their blood. This substance is a chemical end-product of muscular exertion. Hence we have a picture of death from overexertion rather than suffocation.

Extinction of Wildlife.

Interesting data have been collected and observations made in the fields of zoology which cannot be termed experimental. Dr. Francis Harper, of the American Committee for Wildlife Protection, has reported that, since the beginning of the Christian era, some 72 species and sub-species of mammals from all over the world have become extinct. This extinction was primarily through the human agency. He reports that the North American record is especially bad. Here, in over 40 years, 24 forms have become extinct. In contrast to this he finds that the extinction record in South America, which is relatively sparsely settled, is zero. Island faunas, he writes, suffer especially. Here you have animals in a limited area, with nowhere to escape to, and hence liable to the attacks of man or certain pests introduced by man.

Communal Habits of the Woodpecker.

William Ritter, Professor Emeritus of Zoology at the University of California, has made a study of some of the habits of a particular species of woodpecker found on the West coast. He has collected his observations on these birds and placed them in book form with the title 'The California Woodpecker and I.' Some interesting observations were based on the sociology of this species. Dr. Ritter writes that this bird is an acorn-storer. It stores the nuts in holes it bores in trees, buildings, etc. However, this enterprise is a communal one, for the woodpeckers all store their acorns in one tree trunk and all help themselves to the same storeroom. They also act together in protecting this store from marauding squirrels. Also, in building nests and even in feeding young, they work in groups of threes and fours.

Revival of Frozen Fish.

A long-disputed notion as to whether fish frozen in liquid air can be revived again has possibly been solved by the experiments of Dr. B. Luyet, of St. Louis University. He immersed goldfish in liquid air for variable periods and then placed them in water at ordinary temperatures. Dr. Luyet found that goldfish completely frozen cannot be revived. However, he found that the ability of the fish to regain its activity depends on the degree of damage done to the tissues: if a fish is frozen only superficially or is only momentarily rigid, it will survive; but if the body walls are injured to any great extent, the fish dies.