278 THEORIES ON THE ORIGIN OF VERTEBRATES 



it, the physiological, orientation of his principle, and he 

 rightly regarded this as one of its chief merits. He held 

 that morphology became too abstract and one-sided if 

 it disregarded physiology completely ; he saw clearly that 

 the evolution of function was quite as important a problem 

 as the evolution of form, and that neither could be solved in 

 isolation from the other. "The concept of function-change 

 is purely physiological ; " he writes, " it contains the elements 

 out of which perhaps a history of the evolution of function 

 may gradually arise, and for this very reason it will be 

 of great utility in morphology, for the evolutionary history of 

 structure is only the concrete projection of the content 

 and course of the evolution of function, and cannot be com- 

 prehended apart from it " (p. /o). 1 



It is very instructive in this connection to note that 

 Dohrn was not, like so many of his contemporaries, a 

 dogmatic materialist, but upheld the commonsense view that 

 vital phenomena must, in the first instance at least, be 

 accepted as they are. " It is for the time being irrelevant," he 

 writes, "to squabble over the question as to whether life is a 

 result of physico-chemical processes or an original property 

 ( Urqualitdf] of all being. . . . Let us take it as given " 



(P- 75)- 



Semper's speculations on the genetic affinity of Articu- 

 lates and Vertebrates are contained in two papers- which 

 appeared about the same time as Dohrn's. He openly 

 acknowledges that his work is essentially a continuation 

 of Geoffroy's transcendental speculations, and gives in 

 his second paper a good historical account of the views of his 

 great predecessor. It is a significant fact that evolutionary 

 morphologists very generally held that Geoffrey was right in 

 maintaining against Cuvier 3 the unity of plan of the whole 



1 Cf. Metsclmikoff, Quart. Journ. Mtcrosc. Set., xxiv., pp. 89-111, 

 1884. 



2 "Die Stammesverwandschaft der Wirbelthiere und Wirbelloscn," 

 Arb. zool.-zoot. Instit. \Viirzburg, ii., pp. 25-76, 1875 ; "Die Verwand- 

 schaftsbexiehungen dcr gegliederten Thicre," Ibid., iii., pp. 115-404, 



1876-7. 



3 Abuse of Cuvier also dates from the early days of evolution, see 

 Racll, ii., pp. 12-17. 



