RECORDS. 385 



pay our humble tribute of admiration and homage to a scientific 

 insight that was capable of reaching such a conclusion in the far 

 away prehistoric period when chromosomes and Mendelism were 

 unsuspected, when the nature of fertilization was unknown, and 

 the internal mechanism of development was a wholly unsolved 

 riddle. 



I will in conclusion add only a few words on the question of 

 vitalism and mechanism in the light of the foregoing results. 

 In so far as development may be conceived as the outcome of 

 an original material configuration in the nucleus, and a secon- 

 dary configuration in the protoplasm, it may be conceived as a 

 mechanical process. But it must be admitted that this concep- 

 tion leaves quite unsolved certain fundamental elements of our 

 problem — such for instance, as the manner and order in which 

 the protoplasmic stuffs are formed and assume their character- 

 istic configuration, whether in the whole egg or in the isolated 

 blastomere or egg-fragment ; or again, how the wonderful 

 phenomena of the regeneration of lost parts in the adult organ- 

 ism can be explained. We have at present no positive data for 

 an answer to these questions. But it can hardly be disputed 

 that we have already made a considerable advance towards a 

 mechanical solution of the problem, and if this be so, by what 

 right does the vitalist demand that we shall adopt his hypothesis 

 for the portions still unsolved ? Let us seek an answer to this 

 question in the answer to a broader one. What is the object of 

 the study of development ? I should state this object some- 

 what as follows : P'irst, to observe and to describe as completely 

 and simply as possible the actual phenomena of development ; 

 secondly, to determine to what extent, from its beginning in the 

 egg to its completion in the adult organism, the process can be 

 formulated in terms of the elementary laws of matter and of 

 motion. But this is only a different way of stating that our 

 object is to ascertain in what measure the operations of de- 

 velopment, under given external conditions, are the result of an 

 original configuration of material particles in the egg. 



Now, I do not need to say that even the approximate accom- 

 plishment of these aims is still very remote, their complete 



