332 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1952 



approach resulted in the later utilization of specific knowledge regard- 

 ing a chemical and physical phenomenon for the identification and 

 localization of the cellular components. 



In spite of our increased knowledge of the cell, the primary prob- 

 lems have changed only in degree, i. e., from morphological to physio- 

 logical. We are still interested in the structure of protoplasm and 

 in its submicroscopic or molecular structure and not as to whether it 

 appears reticular, fibrillar, or granular in nature. The cytologist has 

 literally joined hands with the chemists, the physiologists, and the 

 physicists in an attempt to unravel the intricate workings of the cell 

 in all the complex phases of its life — development, maintenance, and 

 reproduction. We are not, however, concerned with these phases per 

 se but instead with the mechanism of cell function during these phases. 



Cell function can be understood only through a knowledge of the 

 intracellular components, that is, the chemical components which make 

 up the cell. At the chemical level, enzymes dominate the scene. 

 Enzymes constitute more than half of the solid matter in most cells. 

 The number of different enzymes and their individual action and re- 

 quirements may be astronomical in number. There is a rapidly grow- 

 ing conviction that cells differ only to the extent that their enzyme 

 components differ. Waddington (1948) characterizes development 

 as essentially a sequence of chemical changes that have secondary 

 physical effects expressed in the morphology of the embryo. Beadle, 

 in his work on Neurospora, postulates a one-gene, one-enzyme relation- 

 ship. One wonders if the gene-enzyme relationship is that direct or 

 that simple. It has been suggested, and there is strong support for 

 the hypothesis, that the nuclear gene expressed itself by means of a 

 cytoplasmic unit, the so-called plasma gene. No matter how the gene 

 makes itself felt, the final action is an enzymatic one. Potter (1950) 

 says, "that when a particular group of enzymes is organized in one 

 way, a liver cell results ; with a slightly different collection of enzymes 

 appropriately organized, a kidney cell results; and with another as- 

 sortment of enzymes, a cancer cell results." If function of either the 

 normal cell in all its phases or the abnormal cancer cell is to be under- 

 stood, the enzyme pattern which characterizes it must be determined. 



Cytology has played and is continuing to play an important role 

 in determining these enzyme patterns. This development results in 

 a new cytology, one which overlaps into the now-related fields of 

 genetics, morphogenesis, biochemistry, cellular physiology, and en- 

 zymology. It is, of course, a cytology based on entirely new tech- 

 niques, i. e., new to the biologist. Many of these techniques were ac- 

 tually borrowed as developed by the chemist and the physicist, while 

 others have been modified to fit the needs of the biologist. These new 

 procedures have made it possible to identify, localize, and in some 



