R. D. HOTCHKISS 



agents as light or electron beams, electric currents, and especially 

 chemicals or enzymes, and noting changes in the cell or the environ- 

 ment caused by whatever interaction takes place. 



Chemotherapy must have had its humble inception in self- 

 medication, the observation of the effect of natural herbs, plants, 

 juices, etc., upon the sick organism. During the course of time this 

 growing branch of medicine has come to make extensive use of the 

 knowledge accumulated by the pharmacologist, and of the materials 

 isolated from nature or synthesized by the chemist. In its present 

 phase, chemotherapeutic medicine is beginning to draw spasmodically 

 upon the pure science of biological chemistry. Despite the commer- 

 cial significance of chemotherapy, we are hardly justified in speaking 

 of a science of "theoretical chemotherapeutics." We shall entertain 

 here the somewhat limited view that chemotherapeutic medicine is an 

 applied cytochemistry. In so doing, we shall be able to look into 

 the future of what are believed to be some current trends, and to 

 consider some of the challenges that face the workers, and their teach- 

 ers, in this important field. 



Perhaps the bright future of cytochemistry may be the better 

 envisioned if a comparison is made between this science and its more 

 established predecessor, organic chemistry. During the last century, 

 the organic chemist has been systematizing his experiences with the 

 effect of chemical reagents upon various complex molecules. He has 

 learned to detect atom groups which react together as units, to look 

 upon one of these groups as the unifying backbone or nucleus of the 

 molecule, and to locate the position of other groups relative to this 

 one. With the recent confirmation of many of his deductions by 

 physical methods, skepticism as to the general validity of his indirect 

 methods appears to have vanished. In a quite analogous way, the 

 cytochemist is beginning to study the way in which whole molecules 

 and layers of molecules are distributed in the living cell. It may be 

 said to be his task to be aware of the constituents of cells revealed by 

 chemical, physical, metabolic, immunological, pharmacological, or 

 nutritional analysis, and to learn to recognize these constituents, and 

 the evidences of their functioning, in the intact cell. Cytochemistry is 

 indeed the area of common interest which eventually will unite bio- 

 chemistry with biology in general. 



Since most cells are large enough to reveal detail in light, or 



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