138 SYMBIOGENESIS 



metabolic conditions of life. It is clear that the growing 

 exigencies of the complex web of life require a continuous 

 increase of symbiotic capacity. Hereditary similarity is in 

 keeping with the identical discharge of hereditary bio-economic 

 duty by progeny, and subsequent dissimilarity fluctuates with 

 the fluctuations in such discharge. 



We have seen that the nutrition essential to progressive 

 diversification and to the co-ordination of cells even in the most 

 primitive social state must, if it is to have permanence, be 

 symbiotically acquired, failing which there is not even a 

 metabolic possibility of successful co-ordination and diversifi- 

 cation, be it for genetic or ordinary social purposes. 



We have found that this is so because the production of 

 nutrition itself, which after all is the first essential, is funda- 

 mentally from first to last a matter of joint production and of 

 division of labour, i.e., it depends on symbiosis. All of which 

 points to the permanent necessity of continuous reciprocal and 

 progressive differentiation of (unit and general) characters, 

 and, if need be, also of various degrees of biological antagonism 

 in accordance with qualification. 



We have already noticed one form of organic antagonism 

 particularly related to Genetics, the classical study of which 

 we owe to Darwin, who expressed his results in the aphorism : 

 " Nature abhors perpetual self -fertilisation," i.e., in-breeding. 



Another form of antagonism which I believe to be more 

 fundamental still, I have expressed in corresponding terms 

 thus: " Nature abhors perpetual in-feeding." And yet another 

 form, also very far-reaching, I believe to be found in the 

 application to the sphere of Biology of Gresham's law of 

 currency, that bad money drives out good money. 



In view of the common (bio-economic) cause of all these 

 forms of antagonism, I believe the underlying truth can be 

 expressed in a simplified form by the German aphorism : 

 "Better is an enemy to good." And thus a simple, homely 

 truth would seem to be at the base of much infertility in 

 nature and of Mendelian segregation. 



