REPRODUCTION 63 



collects them into the same body, co-ordinates them 

 and causes them all to work together for the com- 

 mon good, and finally splits off from itself small 

 fragments not in any way resembling itself, from 

 which, however, by a process of growth and de- 

 velopment, further crystals like unto the congeries 

 which we have been imagining are developed. 

 Perhaps it will be said that the comparisons just 

 made are crude and coarse and cannot fairly be 

 taken as representing the delicate processes of 

 nature. This may be freely admitted, but such 

 comparisons bring out the difficulties which there ; 

 are in accepting the mechanical theory of nature [ 

 and, one may also say, exhibit the profound differ- 

 ences which exist between the inorganic and the 

 organic worlds. 



This argument is greatly strengthened when 

 one takes into consideration the facts which have 

 been elicited by the experimental study of develop- Experiment* 



i TC ^i jr in embry- 



mg ova during recent years. It there is one thing ology 

 which is quite clear about chemical and physical 

 processes it is that they are rigid and unvarying. 

 So far as we know a certain result is attained by 

 one series of steps and by that series alone, and 

 any interference with that series leads to a collapse 

 of the whole affair and a failure to achieve the 

 end which would otherwise have been reached. 

 This is not the case in the process of develop- 



