150 CLELAND 



fundamental attributes, whether they belong to bacteria, the higher plants, 

 or animals. An agent or condition which effects the functioning of one kind 

 of cell is likely to have similar effects on other cells. Many of our most 

 pressing biological problems involve the cell and the behavior of protoplasm. 

 Cancer, for instance, is a condition in which cells have lost the inhibitors 

 which retard and control growth and cell division. The brakes have been 

 released, and the processes of growth and multiplication are unrestrained. 

 The solution of the cancer problem will not be achieved by attempts to cure 

 cancer, nor will it necessarily come by the study of human tissues, since 

 cancers are found in many other organisms, even in plants. It will not be 

 found until we know what makes cells grow and multiply, what controls 

 and regulates these processes, what substances are capable of throwing a 

 monkey wrench into the regulatory machinery, and what part of the ma- 

 chinery they affect. Then, and only then, will we be in a position to take 

 the necessary measures to prevent the uninhibited growth of cells or to arrest 

 such growth once it has started. Since the essential machinery is the same 

 in all kinds of cells, this problem can be attacked by the study of any kind 

 of cell. It will not be surprising if some of the keys to the solution of the 

 human cancer problem (there probably is no one key) will be discovered by 

 studies of plant cells. The more widespread the study of the mechanism of 

 cell growth and division, the sooner the essential clues will be discovered. 



This is but one illustration of the fact that, at the cellular level, all life 

 displays a unity which superficial observation of plants and animals fails 

 to reveal. Protoplasm in all organisms is organized in essentially the same 

 way. In basic behavior and characteristics, protoplasm is essentially the 

 same in all organisms, though it is obvious that in the finer details of chemi- 

 cal composition and organization, the protoplasms of different organisms dif- 

 fer. It is the presence of protoplasm which distinguishes the living from the 

 lifeless. 



This unity is something which involves not only plants and animals. It 

 includes man as well. Detailed study of cellular structure and protoplasmic 

 behavior in man shows that these are essentially the same as in other organ- 

 isms. The chromosomes in man are typical in structure and behavior; they 

 divide in normal fashion and are distributed to sperm and egg in the usual 

 manner. Thus the physical basis of heredity is the same in man as it is in 

 animals and plants. There is no reason to suppose, therefore, that man is any 

 different from the plants and animals from the standpoint of heredity, or of 

 the mechanism by which his characteristics are determined and transmitted 

 from parent to offspring. His characteristics are as fully gene-controlled and 

 as fully dependent on chromosome behavior as are the characteristics of 

 fruit flies and lilies. Since intensive studies of many organisms have shown 

 that gene control extends not only to external or structural features, but also 

 to the physiological processes, even to the behavior of the chromosomes 



