56 THE CONTROL OF LIFE 



others are rather qualitative, some novel pattern. They 

 are individual variations. Whether they have come to 

 stay or not time will show. 



Under the breeder's supervision a single variant may 

 become the source of a constant race, as was the case 

 with the once famous short-legged Ancon sheep (1791), 

 the American Polled Herefords (1889), the Calif ornian 

 seedless orange, and so on. To obtain a pure race of 

 wheat or the like, e.g. with qualities suited for particular 

 soils, it is now usual, as at Nilsson's Institute at Svalov 

 in Sweden, to start from the seeds of one promising head. 

 But it does not always happen that a variant in itself 

 very promising is able to ' hand on ' its good qualities to 

 its offspring. In Professor Raymond Pearl's work on good- 

 laying hens (up to the 200 eggs a year standard) it was 

 found necessary to make sure not merely that the mother 

 hen was a very good layer, but that her daughters were 

 so likewise. An individual excellence is not necessarily 

 continued in the next generation. 



§ 3. Fundamental Facts of Heredity 



(1) Heredity is a flesh and blood linkage, a germinal 

 continuity, binding generation to generation. It is 

 a term for a biological relation of offspring to ancestry. 

 It has nothing directly to do with tradition or with 

 culture legacies handed on outside the organism. 



(2) The natural inheritance is carried, we cannot 

 picture how, in the form of initiatives, or factors, or 

 determinants in the egg-cell (the ovum) and the sperm- 



