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SCIENCE 



[N. 8. Vol. XXXIX. No. 1002 



of the older subjects they shall supplant, he 

 can not but hesitate. Which of these true 

 and tried teething-rings of our zoological 

 infancy shall be discarded? Can we spare 

 any of them? I must confess that after 

 considerable pondering I have concluded 

 that for the training of the professional 

 zoologist or the teacher of zoology I do not 

 see how we can. I can find ways for short- 

 ening them to make room for new subjects 

 and ways for injecting new meanings into 

 them from our late fields of discovery, but 

 it seems to me that when all is said and 

 done, comparative morphology, including 

 embryology, together with some histology, 

 is a well-nigh indispensable ballast for our 

 ship of biological progress. None of the 

 newer experimental lines can yet take the 

 place of these for training the zoological 

 apprentice. I have yet to find the subjects 

 in which I can pin my students down to ex- 

 act observations, unequivocal inference and 

 far-reaching generalizations in the concen- 

 trated form I can secure in a course of 

 study based on morphology, but saturated 

 throughout with demands for interpretation 

 of the structures under consideration in 

 terms of function and environment. 



It seems to me, moreover, that nearly all 

 of these newer lines actually or tacitly pre- 

 suppose a considerable amount of system- 

 atic or morphological training. Much 

 of our experimental zoology has bearings 

 on the problems of evolution; hence what 

 can such work mean to a student who has 

 not reached an understanding of organic 

 evolution from a careful comparative study 

 of animals of different degrees of complex- 

 ity ? Or of what avail are many of the ef- 

 forts of our statistical friends, the biome- 

 tricians, without a keen appreciation on our 

 part of the questions at issue, based funda- 

 mentally on an understanding of the real 

 significance of variations ? Or in the realm 

 of animal behavior, one of the insistent new 



claimants for attention, the facts have 

 meaning mainly as interpreted from the 

 comparative or the evolutionary point of 

 view, which presupposes knowledge of the 

 relative complexities of the fundamental 

 types of nervous systems. Of what signifi- 

 cance, for example, is Professor Jennings's 

 trained starfish, except as understood in 

 terms of our knowledge of the starfish nerv- 

 ous system and the animal's relative posi- 

 tion in the animal kingdom? 



Or, taking the field of experimental em- 

 bryology, how far should we get in true sci- 

 entific appreciation of the recent work on 

 tissue culture in vitro had we not consider- 

 able preliminary familiarity, not only with 

 the structural nature of tissues but with 

 general embryology as well ? And when it 

 comes to the quest for organ-forming sub- 

 stances, cytoplasmic prelocalizations or 

 whatever we may be disposed to call pre- 

 cleavage differentiation, certainly the neo- 

 phyte can travel the road towards under- 

 standing but a short distance without 

 considerable preliminary knowledge of or- 

 ganogeny and even of cytology. Or again, 

 in the field of genetics, while some of the 

 practical values may be understood and 

 utilized by those having meager knowledge 

 of other biological facts, the full apprecia- 

 tion of the new discoveries can be grasped 

 only by the well-rounded student, conver- 

 sant with modern points of view in the 

 fields of variation and evolution, embryol- 

 ogy, cytology and general zoology. 



Coming to cytology, no one, I think, will 

 gainsay the statement that it is highly de- 

 sirable for students to have had preliminary 

 courses in comparative zoology, histology 

 and embryology, to say nothing of a grasp 

 of the problems of heredity and variation. 



At the very outset of our planning, of 

 course, we are met with the question, which 

 of our students are we planning for? The 

 five or ten per cent, who may become pro- 



