INTRODUCTION. 5 



and not the outcome of blind force. Who could 

 look upon the adaptation of the eye to light with- 

 out seeing in it the result of intelligent design ? 

 Adaptation to conditions is seen in all animals and 

 plants. These organisms are evidently compli- 

 cated machines with their parts intricately adapted 

 to each other and to surrounding conditions. 

 Apart from animals and plants the only other 

 similarly adjusted machines are those which have 

 been made by human intelligence ; and the infer- 

 ence seemed to be clear that a similar intelligence 

 was needed to account for the living machine. The 

 blind action of physical forces seemed inadequate. 

 Thus the phenomena of life, which had been stud- 

 ied longer than any other phase of nature, con- 

 tinued to stand aloof from the rest and refused to 

 fall into line with the general drift of thought. 

 The living world seemed to give no promise of 

 being included among natural phenomena, but 

 still persisted in retaining its supernatural as- 

 pect. 



It is the attempt to explain the phenomena of 

 the living world by the same kind of natural forces 

 that have been adequate to account for other 

 phenomena, that has created modern Biology. So 

 long as students simply studied animals and plants 

 as objects for classification, as museum objects, or 

 as objects which had been stationary in the his- 

 tory of nature, so long were they simply follow- 

 ing along the same lines in which their prede- 

 cessors had been travelling. But when once they 

 began to ask if living nature were not perhaps 

 subject to an intelligent explanation, to study 

 living things as part of a general history and to 

 look upon them as active moving objects whose mo- 

 tion and whose history might perhaps be accounted 



