Glass • Genetics in the Service of Man 



251 



and today, by means of the drug 

 colcliicine, it has become casv to dou- 

 ble the chromosomes of a hybrid, just 

 the step where Karpechcnko met his 

 greatest difficulty. 



There is, at any rate, no difficulty 

 in controlling the amount of genetic 

 intermixture h\ performing, on the one 

 hand, the desired crosses, and on the 

 other by isolating and otherwise pre- 

 venting intermixture, just as man in the 

 past has controlled the interbreeding 

 between different breeds of dogs or 



cats. As to the fourth factor, this too is 

 under human control because it de- 

 pends particularly on the size of popu- 

 lation, which may be readily regu- 

 lated. 



At this point one might feel like 

 singing, with Swinburne, "Glory- to 

 Man in the highest, for Man is the 

 Master of things." But one had better 

 be war}\ Problems aplenty remain just 

 as soon as one begins to consider the 

 application of this newfound genetic 

 power to Man himself. 



QUESTIONS 



1. Comment on two of the major bio- 

 logical discoveries made in recent 

 years. 



2. What problem does mold mutation 

 present to the scientist and to the 

 physician? 



What two men have done most to- 

 ward warding off the Malthusian 

 threat of an inadequate food supply? 

 Briefly describe their work. 



Discuss the four major factors con- 

 tributing to evolutionary change. 



