INTRODUCTION. 13 



and the unexplained. The phenomena associated 

 with living things remained nearly as mysterious 

 as ever. Life appeared to be the most inex- 

 plicable phenomenon of nature, and none of the 

 forces and laws which had been found sufficient to 

 account for other departments of nature appeared 

 to have much influence in rendering intelligible 

 the phenomena of life. Living organisms appeared 

 to be actuated by an entirely unique force. Their 

 shapes and structures showed so many marvellous 

 adaptations to their surroundings as to render it 

 apparently certain that their adjustment must 

 have been the result of some intelligent planning, 

 and not the outcome of blind force. Who could 

 look upon the adaptation of the eye to light 

 without seeing in it the result of intelligent 

 design 1 Adaptation to conditions is seen in all 

 animals and plants. These organisms are evi- 

 dently complicated machines with their parts 

 intricately adapted to each other and to sur- 

 rounding conditions. Apart from animals and 

 plants the only other similarly adjusted machines 

 are those which have been made by human in- 

 telligence ; and the inference 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 studied longer 

 than any other phase of nature, continued 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 aspect. 



