LINNEAN SOCIETY OF LONDON. 2$ 



advance in the complexity of adaptations, and by an increase in 

 the powers of control and foresight exercised by the foremost 

 part of the central nervous system. On these t^A'o factors, fore- 

 sight and control, depends a man's position among his fellows, 

 and a continuous growth in the same factors marks the pro- 

 gression of living forms from the Worm to the highest Vertebrate. 

 Since the functions which determine survival are those bound 

 up almost exclusively with the central nervous system, this system 

 is taken by Gaskell as his guide in tracing the genealoijy of the 

 Vertebrate. 1 am not sufficiently equipped to bear testimony in 

 favour or otherwise of the facts adduced by Graskell in support of 

 his theory. I am convinced, however, that the principles on which 

 he has proceeded are the only ones which Mill lend to a solution 

 of the problem, and that researches along these lines will throw 

 light on the meaning and physiological significance of many organs 

 whose part in the economy of the body is still a mystery. It is 

 difficult to understand the attitude which has been taken up by 

 the majority of zoologists towards this theory of the origin of 

 Vertebrates. We find zoologists themselves putting forward 

 theories of the descent of Vertebrates based on a more or less 

 profound study of all sorts of organs and structures which really 

 have little or no importance in the life of the animal, or can be 

 replaced vicariously or structurally with the utmost ease. Thus 

 they concentrate their attention on or{j;ans such as the alimentary 

 canal, blood vessels, foetal membranes, excretory organs, the 

 notochord, but p:iy little or no regard to the one system of the 

 body which is all-important in determining the continuous series 

 of adaptations which make up the life of the animal. And what 

 is strange is that in most cases no palaeontological evidence seems 

 to be brought forward in favour of these hypotheses. I do not 

 know whether succeeding speakers will be able to adduce any facts 

 from the geological record in favour of the existence of the strange 

 slug-like animals, with or without holes punched in them, which 

 have been evolved out of the inner consciences of our most dis- 

 tinguished zoologists and assigned to us as our remote ancestors. 

 To an onlooker like myself the striking resemblance between the 

 earliest fishes and the Arthropoda which were the dominant type 

 just before the appearance of these Vertebrates, is striking evidence 

 in favour of Gaskell's theory. I would ask the morphologists 

 present here to-night to explain how they account for this striking 

 similarity. If the gastrula theory had been mentioned in the 

 first chapter of Genesis, it is possible that the presence of those 

 earliest fishes in the earth's crust might be regarded as a divinely 

 appointed trial of faith for the orthodox among zoologists. It 

 seems to me that the morphologist, while professing a lip service 

 to the doctrine of Evolution, has really forsaken the teachings of 

 Darwin and gone back to the worship of his old idol, the study of 

 form for itself. For him, as for the anatomists before Darwin, 

 similarity of form is everything and function is of no account. 



