ii4 SYMBIOSIS 



due acknowledgment, took exception to the following, oft- 

 quoted passage from the Origin : 



In the case of the mistletoe, which draws its nourishment from certain 

 trees, which has seeds that must be transported by certain birds and 

 which has flowers with separate sexes absolutely requiring the agency 

 of certain insects to bring pollen from one flower to another, it is equally 

 preposterous to account for the structure of this parasite with its relations 

 to several distinct organic beings by the effect of external conditions, or 

 of habit, or of the volition of the plant itself. 



Certainly it would not do to account for this case with any 

 one of these factors alone. We require an explanation that does 

 justice to all the factors. The question, however, is, to which 

 of these factors we are to assign chief importance. In my 

 opinion, it is to " sociological "or bio-economic factors standing 

 out prominently even in Darwin's account that the chief 

 importance is due. 



Butler protests that Darwin makes the case of the mistletoe 

 look more formidable than it really is. Yet, it is clear that he 

 himself cannot here fully meet the difficulty. He says this r 



Neither plant nor bird knew how far they were going or saw more 

 than a very little ahead as to the means of remedying this or that with 

 which they were dissatisfied, or of getting this or that which they desired ; 

 but given perceptions at all, and a sense of needs and of the gratification 

 of those needs, and thus hope and fear, and a sense of content and dis- 

 content given also that some individuals have those powers in a higher 

 degree than others given also continued personality and memory over a 

 vast extent of time and the whole phenomena of species and genera 

 resolve themselves into an illustration of the old proverb, that what is one 

 man's meat is another man's poison. 



A critic might justly say that this explanation is too purely 

 psychological, that it fails to do justice to the biological (bio- 

 social) factor, and that the answer that " what is one man's 

 meat is another man's poison " provides too superficial an 

 account of the diversification of species and genera with their 

 manifold and important correlations. This proverb furnishes 

 far too bald a statement of the biological law, which, according 

 to Butler's own subsequent inspirations, involves a number of bio- 

 or quasi-moral obligations on the part of the organism. 

 The bald explanation merely slurs over inter-connectedness. 

 It may be true in a sense, in the case of the mistletoe, that plant 

 and bird (and cross-fertilising insect) each and all merely stumbled 

 upon their special relation, which yet proved of great mutual 



