22 president's address. 



for the manufacture of soap, but is inactive toward an acid 

 liquid." 



Again, one may ask, is not the repair of mutilated crystals a 

 phenomenon which is worthy of being placed alongside the no 

 doubt far more complicated phenomena connected with the self- 

 repair of organisms 1 The regeneration of the other half of a 

 hemi-gastrula resulting from the destruction in situ of one of the 

 first two blastomeres of a developing ovum, however determined, 

 must involve most highly complicated material rearrangements, 

 and the process in the present state of knowledge must be 

 admitted to be practically unintelligible as a mechanical procedure. 

 But can one say so very much more with respect to the regenera- 

 tion of the ideal form of a crystal which has undergone mutilation 1 



No one, I take it, would submit these parallels as of equal 

 degrees of complexity. Yet, though the phenomena concerned 

 may be widely incommensurate, as purely objective phenomena 

 they suggest somewhat analogous explanations. 



In the latter portion of his paper Dr. Haldane seeks to point 

 out the " way out of the difficulty in which the shortcomings 

 of both the physico-chemical and vitalistic theories have placed 

 physiology." 



This attempt he makes with the aid of an appeal to the modern 

 development of scientific anatomy or morphology. 



" The fundamental assumption of morphology is," he says, 

 " that each part of an organism is determined as regards 

 its mode of existence by its relations to other parts. That 

 this determination is real and not merely apparent, is shown by 

 the facts ( 1 ) that morphological plan is so persistent in spite of 

 disturbing influences ; (2) that parts which are removed tend to 

 be reproduced." It is this conception of a morphological plan 

 which is regarded as the vivifying principle of modern anatomy. 

 In other words, it is the idea of homology as morphological 

 identity. I think that upon the whole it is correct to say that it 

 is this idea which is specially characteristic of the morphology of 

 the latter half of the century. But it seems to me that the real 

 ground of the principle as operative in modern science is entirely 



i 



