- INTRODUCTION 31 



Weismann says, in reference to such researches, 

 " We should not be able to perceive the results 

 of a successful experiment," we must agree with 

 him, of course, that we could not perceive the 

 initial combinations and all the stages that lie be- 

 yond the range of our aided vision; but when 

 the previously invisible, newly-evolved germs grow 

 into minute but definite organisms, we surely 

 could perceive the results of our successful experi- 

 ments. Similar reasoning would just as much 

 entitle Weismann to say that we never could per- 

 ceive the birth of a crystal from its mother liquor 

 because its initial combinations would lie alto- 

 gether beyond the range of our vision, however 

 aided. Nevertheless, we know full well that crys- 

 tals appear and grow in this or that fluid into 

 prismatic, hexagonal, and other forms, just as we 

 may assume that the new-born units of living 

 matter, as they come into the region of the visible, 

 may take on the shapes of Micrococci, Bacilli, and 

 Torulse. If these are the forms that appear in 

 the experimental vessels, we should necessarily 

 have to conclude that new-born units of living 

 matter speedily take definite but highly variable 

 forms, just like new-born units of crystalline 

 matter. 



