136 THE FUTURE OUTLOOK 



The situation is the same in comparative biochemistry. At 

 present comparative biochemistry is founded on the results ob- 

 tained on a small number of so-called typical animals, plants, 

 yeasts, and bacteria. The sole basis of the claim that these or- 

 ganisms are typical rests upon the facts that all of them may, 

 by rather simple methods, be obtained in great quantities and 

 that many of them have been prominent in the preliminary medi- 

 cal biology courses and their equivalents. The great majority of 

 living organisms cannot be obtained in sufficient quantity for 

 biochemical studies without immoderate and unjustified expense. 

 But cytochemistry has the potentiality of throwing almost the 

 whole of the living world open to study by the chemist. 



Medicine and agriculture cannot fail to benefit from the funda- 

 mental studies just outlined, but in addition to this there is prom- 

 ise for the direct sudy of pathological conditions by cytochemical 

 methods. For example, studies of gene action, of the evolution 

 of genes and viruses, and of differentiation hold great promise 

 for the elucidation of the nature of cancer and the development 

 of new drugs for the treatment of cancer. It has already been 

 shown that various tumours are particularly rich in certain 

 enzymes. This in itself has been effective in promoting the study 

 of new types of drugs. The drugs which are in use at present 

 lack selectivity so that, although they have a potent action on 

 tumour cells, their use is restricted by their high general toxicity. 

 At King's College we are now investigating the use of drugs 

 which are comparatively inert, but which, upon coming into con- 

 tact with an enzyme present in high concentration in a tumour 

 cell, liberate a derivative of very high activity. Thus we hope 

 that, by designing a drug to fit the enzymic pattern of a tumour, 

 we may attain a much higher degree of specificity of drug action. 



Equally, we can expect assistance in diagnosis. A biopsy speci- 

 men can seldom provide sufficient material for a variety of bio- 

 chemical tests, but it is sufficient for dozens of cytochemical tests. 



Thus the outlook in cytochemistry is full of promise. This 

 promise, however, will only be fulfilled if cytochemistry is used 

 as a rigorous technique by an adequately trained staff. 



REFERENCE 



Coons. 1952. Symp. Soc. Exp. Biol., 6 (in press). 



