BASIC LIFE.

Auckland Star, Volume LXVII, Issue 167, 16 July 1936, Page 16

BASIC LIFE.

THEORY DISPUTED.

RESEARCH BY SCIENTISTS.

A NEW HYPOTHESIS

(By THOMAS R. HENRY.)

WASHINGTON, June 10,

Turning upside down generally accepted concepts of the basic mechanisms of life and denying the gene theory of heredity, Dr. E. E. Just, professor of zoology at Howard University, has just announced, after more than 20 years of experimentation with the ultimate units of living things, an hypothesis which bridges the gulf between development and genetics. The paper issued by Dr. Just, if it finds any general acceptance among zoologists, is revolutionary in its implications to the biological science of the future. It places the origin of life and its development through evolution in a new and simpler light. It explains such anomalies as cancer, and promises an entirely new field of therapeutic attack. In fact, Dr. Just says, he himself now is at work on a hopeful way of reversing the process which, he has shown, results in uninhibited cell growth in some of the lower organisms. It throws new light on such obscure biological phenomena as multiple births and regeneration of lost parts by some animals. Accepted Conclusions Disputed. The new hypothesis, which flies in the face of the theories of the most eminent living biologists, is based on precision experiments of the Washington professor in the United States, Italy and Germany, where he served as a guest professor. He disputes flatly conclusions of such biologists a.s Dr. Frank R. Little, president, and Dr. T. H. Morgan, past president, of the National Academy of Sciences. The basic experimental work has been the painstaking determination of the weight of the nucleii of the eggs of hundreds of organisms such as sponges, echinoderins and worms. Dr. Just's thesis, in brief, is that the genes, supposed units of heredity, do not themselves contain the potentialities of the heredity qualities they are supposed to transmit, but act by withdrawing from the cytoplasm of the cell everything except the substance which will develop in a specific direction. What the genes withdraw depends in turn on the shape assumed by surface of the cell. The genes, under this theory, act as inhibitors instead of activators. Certain human embryonic material can form only certain kinds of brain cells or certain kinds of hair cells, because the potentiality of everything else has been withdrawn from the cytoplasm at that point by the genes. It has been "locked up." There is some disturbance of the cytoplasm which releases from the genes some of the bound-up material. If enough is withdrawn the cell loses its specificity altogether, and the result is uninhibited growth—the very phenomenon found in malignant tumours. Dr. Just has been able to "unlock" the genes with ultra-violet light radiation. The problem, he says, is to find some way of "locking them." Much the same phenomenon on a controlled scale takes place with certain lower animals, which are able to grow a. new head, or new limbs, after an injury. Living things, plant or animal, start is eggs. The egg is a pluri-potent single jell, the unit of the structure of life, ft is composed of two essential parts — the nucleus and the cytoplasm. The nucleus consists of microscopically risible bodies, the chromosomes, which, n turn, are made up of ultra-microscopic the genes. This nucleus is imbedded in supposedly undifferentiated protoplasmic material, the cytoplasm. How Life Starts. The first step in the life of a multilellular creature is when the singleelled egg splits in two. Then the two lalves split in turn. Then the four larts split —and so on billions of times. Che end result is the plant or animal— he tree, the ant, the human being. Cacli time a cell splits the cleavage is xaet. Each new cell consists of half f each gene and half of all the cytoplasm that was in the parent cell. A simple example is the hen's egg. (bviously everything that is in the ewly hatched chick must have been in J l6 egg. With the insignificant excep* ion of some gases nothing gets in or ut. An infinitely minute part of this gg in the beginning is the egg proper, he rest—the white and the yolk—is here solely for the nourishment of the eveloping oragnism. It is not cytolasm, per se. It is material which can e transformed into cytoplasm. In the mammal the same material has to be obtained from the body of the mother. This first pluri-potent cell splits. There are two cells, each half the size of the first. Actually, the mass of the ' two is a little greater than the one, and —this is the essential basis of Dr. Just's whole_ hypothesis—the mass of the two nucleii or aggregations of genes is minutely greater than the mass of the single nucleii, and the mass of the cytoplasm is minutely less. The nucleus has grown. It must have obtained the extra material from somewhere. The only place from which it could have got it, Dr. Just says, is the cytoplasm. The nucleus has withdrawn some cytoplasm into itself. Now, Dr. Just holds, the effect of this withdrawal is to inhibit the potentialities of the cytoplasm. Either of the two cells cannot do as much as could the parent cell and so on until the three fundamental layers of cells that make up the animal .body are developed. At some point the!genes withdraw the cell potentiality for (becoming skin or nervous system and restrict it to becoming kidney or liver. Thus it continued, through more and more minute differentiations, until the complete body is formed. Always the nucleus is growing at the expense of the cytoplasm. It may have been one part in a thousand at the start. At the end it is a thousand parts to one. • Here two supposedly distinct processes begin to make their appearance. The first is development. The cleavage product of the human being develops the body form and organs of the human being. A hen's egg never gives rise to the rabbit nor a gorilla egg to a rat. First Cell Complete. In some way offspring inherit manness, rat-ness, etc., and in Nature's economy there is never any confusion in this field. Humanity is inherent in the first cell from which man arises. That cell always contains the potentialities of his hands and his brain, which are not contained in the primal cells of his nearest relatives. One can bo sure that the product of a human cell will be some j sort of a human being. '

The second process is that of specific inheritance. Offspring tend to resemble their parents not only in general, but in details. In many cases this specific inheritance follows a mathematical formula. The children of blue-eyed, light-haired parents, passing over complicating factors, will have blue eyes and light hair. They may even inherit such complex things as mental and personality qualities. During the past century this specific inheritance has been attributed to the ultra-microscopic genes in the egg. Each gene, it was supposed, in some way or other, determined some one quality or, by tlie interaction of several, a group of qualities. There was a gene for blue eyes or black eyes, for big feet or small feet. But here is an apparent contradiction. Every gene in the original egg cell splits over and over again and is present in every cell in the body. There are exactly the same genes in a cell of the big toe as in a cell of the eye. What differentiates their action, depending on what part of the body they are in ? This has been a high hurdle for geneticists. " Cytoplasm Contains Everything." . Through his experiments with the eggs and developing cells of certain lower organisms, Dr. Just says, in his report of his work, he found a curious weakness in these hypotheses. The number of splits ran into the billions. Each time the material in the genes was divided in two. Yet it never was exhausted. It was building up from somewhere. The only possible source from which it could be built up was the cytoplasm itself. Thus the nucleus constantly was drawing material out of the cytoplasm. Prom this arises his developmentgenetics bridge. The genes, per se, are not the carriers of heredity at all. Everything is contained in the cytoplasm. The function of the genes is a subtractive one. When the point of making eyes, for example, is reached, the genes have withdrawn from the cytoplasm everything but the specific material which can develop in no other way. The first few splits, for example, result in the withdrawal from the human cytoplasm of the possibility of multiple birth. Then the process continues, always working toward greater and greater specificity, up to the extreme specificity of nerve and brain cells. Thus Dr. Just denies in toto the almost universally accepted dictum that the genes a-re the carriers of heredity, per sc. They are simply part of the mechanism by which the heredity in the cvtoplasm is able to assert itself.— (N.A.N.A.)