Vol. Ill, No. 2 



June, 1928 



The Quarterly Review 

 of Biology 



HOMOLOGY, ANALOGY AND PLASIS 



By JOHN TAIT 

 Department of Physiology and Experimental Medicine, McGill University 



IN THE days of Spallanzani and of 

 John Hunter comparative anatomists 

 did not scruple to employ experi- 

 mental means as an aid to investiga- 

 tion. In their time no hard and fast 

 distinction had been made between 

 questions pertaining to structure and 

 questions pertaining to function. Func- 

 tion and structure being viewed as more or 

 less of a unity, biologists felt free to 

 employ any available means in the investi- 

 gation of their multifarious problems. 

 In the process of historical development 

 physiology hived off from anatomy and 

 very soon two distinct sciences, each 

 employing its own special technique and 

 animated by its own particular aims, had 

 replaced the more generalised biology of 

 Hunter. During the nineteenth century 

 the separation between them became pro- 

 found. Of recent years we have witnessed 

 a strong tendency on the part of zoologists 

 and anatomists to recur to the experi- 

 mental method. It began with Darwin 

 and to a less degree with Milne Edwards. 

 It received a very strong impulse in a 

 special direction from Wilhelm Roux 



and in another direction from Gregor 

 Mendel. More particularly in America, 

 where a strong group of men, prepared in 

 Johns Hopkins University by the joint 

 labors of Brooks and of Newell Martin, 

 were ready at an opportune moment to 

 develop and greatly to extend the biology 

 of Roux and of Mendel, zoology is now 

 viewed as an experimental rather than as 

 a comparative science. In process of time 

 no doubt matters will readjust themselves 

 and the comparative method of studying 

 structure will again come more into vogue. 

 When it does it too will have to be 

 handled experimentally. 



As physiologists are not generally 

 aware of the opportunity open to them of 

 participating in some of the classical 

 problems of comparative anatomy, and 

 as the morphology of our fathers has for 

 the moment fallen on evil days, it seemed 

 worth while to go over the history of the 

 original separation between physiology 

 and comparative anatomy with a view to 

 make some constructive attempt towards 

 a rapprochement between them. The whole 

 issue is rather a wide one and cannot well 



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QUAE. BEV. BIOL., VOL. Ill, NO. 2 



