178 SYMBIOGENESIS 



achieved is also abundantly shown in nature. Redundancy 

 itself I consider to be due to degeneration. It is known that 

 some plants are highly self-fertile (i.e., redundant) when 

 insects are excluded, others are not. 



Ipomea purpurea was one of the highly self -fertile species 

 in Darwin's experiments, and here he found a (retrograde) self- 

 fertilisation so great (and apparently so successful) that he 

 termed one seedling " Hero." " Hero " appeared in the sixth 

 self-fertilised generation and " exceeded by a little in height 

 its inter-crossed opponent a case which had not occurred in 

 any previous generation." "Hero" was able to transmit its 

 increased tallness and a high degree of self-fertility to its 

 offspring. 



Generally speaking, however, in Darwin's experiments, 

 the advantage of vigour and of health lay with the cross- 

 fertilised plants, and as the argument from mere bulk and 

 mere numbers is by no means convincing as to real or 

 permanent success, and as even these carefully planned experi- 

 ments must needs have been somewhat artificial seeing that 

 bio-economic correspondences were but inadequately taken into 

 account we may be sure that an exceptional case of apparently 

 successful self-fertilisation represents a retrograde compati- 

 bility always a contingency under tempting conditions of 

 surfeit or its equivalent, and particularly so with plants already 

 inclined to be self-fertile, i.e., less reliant than others on 

 biological symbiosis. To obtain an expedient (domestic) gain 

 at the expense of biological (communal) integrity is always a 

 possibility ; but in reality it amounts to a retrogression and 

 finally to a loss for the species. If several organisms similarly 

 inclined unite, be it economically or genetically, they do so 

 under what I call a retrograde compatibility, and the result is 

 a pathogenesis. 



In Nutrition and Evolution I have already pointed out 

 that " apparent " incongruities were bound to arise, and this 

 naturally misled Darwin, and almost made him doubt the truth 

 of his great generalisation concerning cross-fertilisation, since 



