﻿Vol. 66.] ANNIVERSARY ADDRESS OF THE PRESIDENT. lxXXI 



us in the end to an ancestral Protist, and thus speculative biology 

 provides us with a new form of the doctrine of predestination. 



The crowd of primitive ancestors which are beginning to inhabit 

 the world of thought are mere logical abstractions, which may never 

 have enjoyed any real existence in the flesh. Unfortunately, they 

 involve another series of equally abstract existences, known as 

 parallel lines of descent ; if these lines in any way resemble those 

 which rest on clearer evidence, they must have been provided with 

 secondary branches, and thus whole phyla are created, which have 

 this peculiarity, that they must have flourished in the past without 

 leaving any trace of their existence in the stratified rocks. 



Primitive ancestors no doubt we must have : they are extremely 

 useful hypotheses serving to fill the gaps, unfortunately too wide 

 and numerous, which interrupt the continuity of our knowledge. 

 But their invention ought not to be a facile task — it should be the 

 concluding effort of a complete review of all the facts ; then only 

 can these hypothetical forms have any claim on our consideration 

 and respect. 



It seems possible that some of the more improbable hypotheses 

 with respect to the descent of Man may have arisen from an imper- 

 fect appreciation of the phenomena of regression. These are 

 acquiring increased importance with our increasing knowledge of 

 extinct forms, and, owing to their abundance in the fossil state, of 

 the marine invertebrates in particular ; among these no group 

 affords more valuable instruction than the Ammonites. As they 

 ascend in time they give rise to species which, in some cases, not 

 only return to the general form and special features of ornamenta- 

 tion that characterize their simpler extinct ancestors, but they even 

 reassume the minute peculiarities of an earlier form of suture-line. 



In several well-ascertained cases the regression is not merely a 

 stopping short at an early stage of the ontogenetic development ; 

 this proceeds till it reaches a climax, and then continues in a back- 

 ward direction. For those who regard development as a phe- 

 nomenon of memory, it is as though the organism, after repeating 

 its lesson in the usual way, had then proceeded to say it backwards. 



Thus an organism or an organ may not only return to a more 

 primitive morphological state, but it may do so by retracing its 

 steps along the very same path as that by which it had previously 

 made its advance. In this way we may arrive at a simpler expla- 

 nation of the primitive characters of the human hand or the human 

 teeth than by an immediate recourse to a remote lemurine ancestor. 

 Even if we were not provided with a knowledge of the laws of 



