ADAPTATIONS 161 



take them as " given," since we do not know 

 how they came to be. We begin within a 

 system and, as we allow no telic factor, we 

 must leave Blind Chance to account for things. /v * 

 Can it do so ? To believe it seems to me to 

 require more credulity than it would to swallow 

 all the Pantheon of Olympus. Dr Johnstone Johnstons 

 is abundantly right when he says* that the 

 factor we have been speaking of is " forced < , * 



upon us mainly because of the failure of the ""' 

 mechanistic hypotheses of the organism. If 1 ' 

 our physiological analysis of the behaviour of 

 the developing embryo, or the evolving race 

 or stock or the activities of the organism in 

 the midst of an ever-changing environment, of 

 even the reactions of the functioning gland, 

 fail, then we seem to be forced to postulate 

 an elemental agency in nature manifesting 

 itself in the phenomena of the organism, but 

 not in those of inorganic nature. This argu- 

 ment, per ignorantiam, possesses little force to 

 many minds : it makes little appeal to the 

 thinker, the critic or the general reader, but 

 it is almost impossible to overestimate the 

 appeal which it makes to the investigator as 

 his experience of the phenomena of the organ- 

 ism increases, and as he feels more and more 

 the difficulty of describing in terms of the 



* Philosophy of Biology, p. 318. 



