42 ON EMBRYOLOGY AS AN AID TO ANATOMY 



delicate methods used in histological research were 

 necessary, and hence for a time embryology was 

 included as a branch of physiology and taught by 

 physiologists. But anatomists soon saw that this 

 science belonged by right to them, and that it was 

 absolutely essential for them to master it. A 

 zoologist of the present day relies quite as much 

 on his razor as his scalpel in his endeavour to 

 comprehend the structure of animals. 



It is not difficult to see how it is that em- 

 bryology has so rapidly attained such importance, 

 the reason being that it has afforded an altogether 

 new and very tangible clue to many of the most 

 interesting problems of biology which have been 

 thereby first brought within the comprehension and 

 grasp of man. Thus the zoologist has in em- 

 bryology obtained a very important clue to the 

 determination of the affinities of animals ; in fact we 

 should hesitate to definitely assign a place to some 

 animals whose development was unknown. To the 

 philosophical biologist a clue is thus given to the 

 determination of what, to him, is the problem of 

 problems viz., phylogeny, or the genetic connec- 

 tion between one animal and another and between 

 their various classes. While to the anatomist em- 

 bryology offers an explanation of many otherwise 

 completely unintelligible anatomical facts. To the 

 members of a medical society anatomy means, and 

 perhaps I may be permitted to say rather too often 

 means, simply human anatomy. I therefore 

 choose for closer consideration a problem, the 

 main conditions of which are familiar to every one 



