swerable questions that confront every naturalist 

 when he attempts to fathom to the utmost depths 

 the meaning of what he sees. 



This question of what constitutes the guiding 

 principal of embryological development that cor- 

 relates its complex phenomena and directs them to 

 a definite end has baffled minds far more compe- 

 tent to cope with them than is mine; so I do not 

 intend to tackle it. However, one cannot long 

 witness these phenomena and escape the conclu- 

 sion that there is a special mechanism involved, 

 behind which is a power transmitted to the struc- 

 ture of the germ-plasm by foregoing generations. 

 But the nature of this power and structure eludes 

 analysis. And it appears that their determination 

 will be long delayed; for as yet we know little or 

 nothing of how the chemico-physical properties of 

 hydrogen and oxygen involve those of even such 

 a seemingly simple substance as water. 



From one of the freshly stocked tumblers on my 

 bench, I selected, with the aid of a glass dipping- 

 tube, several tiny dark spherical dots — each 

 slightly smaller than the period that ends this 

 sentence — from among the numbers of other eggs 



[97] 



