GENETICS 133 



artificial breeding, but that it may be a natural process, which 

 for its accomplishment requires prolonged time." 



That ample time is, of course, necessary for the establish- 

 ment of high bio-economic status and specialisation is evident 

 on my theory, which demands a combined and protracted 

 nutritional and sexual gestation, a building up of values by 

 steady and continuous accumulation, and the gradual 

 establishment of an ever-widening circle of co-operation and of 

 exchange of values in short, a protracted symbiogenesis in a 

 complex web of life. But that the length of time taken in the 

 accomplishment of such desirable results is not fairly to be 

 compared with that of artificial, non-symbiotic or even anti- 

 symbiotic or pathogenetic developments is also evident. 



"Let us look at Mendelian inheritance," suggests Mr. 

 Shelton, " not as the normal form of inheritance, but as a 

 modified form of mutual infertility. Mendelian inheritance is 

 the characteristic of stocks that do not truly blend, and the 

 different varieties emerge from the process of inter-crossing 

 practically unchanged. This clearly tends to fix the types of 

 the crossing varieties." 



This is an interesting view which is well worth con- 

 sidering, and provides a convenient introduction to an inquiry 

 from the symbiogenetic point of view into the subject of 

 Mendelian inheritance now so prominently before the scientific 

 world. 



We have seen the need of wholesome diversification, i.e., 

 of progressive bio-economic specialisation. It is inherently 

 probable that there must be in nature manifold provisions for 

 rendering such wholesome diversification secure from the 

 swamping effects of inferior physiological strains (from inferior 

 physiological currency) ; in the same way as we find especially 

 valuable parts of the body, the brain and the germ-substance, 

 for instance, specially isolated and protected in many ways. 

 It may be, as Mr. Shelton suggests, that usually when 

 Mendelian segregation appears, this is an indication that the 

 previous crossing of the respective pair of "allelomorph" 



