GENETICS 129 



that the organism is or has to start with in virtue of its 

 hereditary relations." 



How do we now account for the fact emphasized by Prof. 

 Poulton of the extreme slowness of progressive evolution in 

 early ancestral types, compared with the rate of progress in 

 more recent times? Prof. Poulton states: "Undoubtedly a 

 study of all the available evidence points to the conclusion 

 that in the lower grades, sub-grades, and Phyla of the animal 

 kingdom, evolution has been extremely slow as compared with 

 that in the higher. We do not know the reason." 



We shall say that in those early days the most powerful 

 factors of evolution, i.e., reciprocal stimulation, reciprocal 

 differentiation domestic and biological symbiosis were but 

 very slightly developed, and that a more rapid rate of progress 

 depended on increasing efficiency of these factors which came 

 about with an increasing complexity of the web of life, and 

 which required and implied increased co-operation, and 

 especially symbiogenesis. 



The increase of co-operative biological interaction, as in 

 the case of international human relations and amenities, pro- 

 ceeded gradually and, at first, slowly. The quickening came 

 later with the spread of higher values and of increasing 

 security of life. 



I have already alluded to Darwin's emphasis of the fact 

 that, " after long intervals of time, the productions of the 

 world appear to have changed simultaneously," as pointing to 

 bio-economic interaction of the kind set forth in the preceding 

 pages. What other cause but that of organic and bio-economic 

 solidarity could have produced inter-connected simultaneous 

 effects of such magnitude and universality, second only to the 

 effects of the force of gravitation? 



Natural Selection? But it is supposed to be an agency 

 working for the good of every individual under its particular 

 conditions, i.e., to be a principle of mere expediency. How 

 could it have produced such simultaneous changes? It 

 "operates" by mutual plunder and death irrespective of the 



