GENETICS 177 



uncouth or hideous shapes, and general repulsiveness of 

 appearance." Hence it is that, inversely, beauty and 

 symmetry are indications that the central authority of an 

 organism is well maintained pari passu with its bio-economic 

 integrity, and hence also we see again that all development 

 of form depends on the total adjustment or compromise which 

 a species is able to effect with the world at large. 

 Prof. Bateson also tells us that : 



If we had to choose some one piece of more proximate knowledge 

 which we would more especially like to acquire, I suppose we should 

 ask for the secret of interracial sterility. Nothing has yet been discovered 

 to remove the grave difficulty, by which Huxley in particular was so 

 much oppressed, that among the many varieties produced under domes- 

 tication which we all regard as analogous to the species seen in nature 

 no clear case of interracial sterility has been demonstrated. The 

 phenomenon is probably the only one to which the domesticated products 

 seem to afford no parallel. No solution of the difficulty can be offered 

 which has positive value, but it is perhaps worth considering the facts 

 in the light of modern ideas. It should be observed that we are not 

 discussing incompatibility of two species to produce offspring (a totally 

 distinct phenomenon), but the sterility of the offspring which many of 

 them do produce. 



Now, what may be the cause of sterility? Physiological, 

 anatomical, psychological ! View it as we may, we are driven 

 back in the last analysis upon the bio-economic cause. The 

 cause is the same as that which produces asymmetry, extreme 

 dimorphism and extinction in nature, namely, the loss of 

 symbiotics and the various forms and degrees of biological 

 antagonism arising from this loss. 



That there must be a kind of "progressive" incompati- 

 bility between different species is explainable, as we have seen, 

 on bio-economic grounds, and so is the usual sterility of 

 Hybrids precariously produced, i.e., under a retrograde com- 

 patibility, lending itself perhaps to reproduction, but less so to 

 stability. 



That there are instances of retrograde compatibility in 

 biological unions, we have seen from the example of Convoluta, 

 and that there are instances of "fertility" retrogressively 



