WALTER HOLBROOK GASKELL LANGLEY. 529 



another, brought forward evidence which was generally regarded 

 as conclusive that chloroform had a direct weakening actFon on 

 the heart. Their paper, published in 1893, checked a tendency to 

 regard the respiration as the only factor to be considered in ad- 

 ministering chloroform. It was a useful piece of work, but it 

 gave Gaskell the only enemy he ever made. 



This investigation was a sidetrack from the main line of the 

 work which Gaskell had been pursuing for some years. His mor- 

 phological studies on the homologies of the cranial and spinal nerves 

 had led him to consider the problem of the origin of the nervous 

 system in vertebrates, and this again led him to a theory of the 

 origin of vertebrates to which he gave nearly all his time in later 

 years. Dr. Gadow has been kind enough to write the following 

 account of this part of Gaskell's researches : 



Gaskell's physiological research has always been to a considerable extent 

 on the morphological side, and this combination of the sister sciences cuhiiinated 

 in his inquiry into the origin of vertebrates. He was drawn to this at present 

 hopelessly difficult problem neither by accident nor design but by the complete 

 failure of various morphological friends to account for certain structures 

 the understanding of which was necessary for his research. He therefore deter- 

 mined to find out for himself, and tims it has come to pass that a man between 

 30 and 40 years of age, M. D. of Cambridge and a physiologist of renown, de- 

 voted about 25 years of his life to essentially morphological studies, more 

 than— in the nature of things — applies to some of his rather bitter scientific 

 opponents. Moreover, entering the new field quite unbiased, his critical miad 

 enabled him^ when studying, for instance, the best comprehensive textbooks 

 on embi'yology, to discover the weak sides of that discipline. It was not a 

 question of picking out what suited him ; on the contrary there was hardly a 

 point — be it the homologies of the germinal layers, the occurrence of some 

 obscure feature like Reissner's fiber, or some Silurian fossil, which he did not 

 take often infinite pains to examine into. Frequently he enlisted friendly help, 

 as in the case of the digestive properties of the Lamprey's skin. 



This is not the place to discuss the strong and weak points of his hypothesis 

 that vertebrates are descended from some Crustacean-like ancestor — i. e., from 

 some vaguely reconstructable stock of which the paliBozolc Trilobites, King 

 crabs, and Scorpions are the only known representatives on the invertebrate side, 

 and he bridged the gulf between them and the vertebrates by the Silurian 

 Ostracoderms, of whose internal organization the larvje of the Lampreys, be- 

 fore their marvellous changes into the present adult forms, seemed to afford a 

 clue. The gulf was great indeed, but his planned bridges were not more hazily 

 sketched than those which pretend to connect the vertebrates either separately 

 or conjointly with Amphioxus, Tunicates, Balanoglossus, etc., with worms and 

 even with Echinoderms. Especially the various worm theories he considered 

 as no solution of the problem, since they would carry the connection so far 

 back as to merge almost into the beginning of the Metazoa, amounting to no 

 recognizable origin. He on the contrary believed that "each higher group of 

 animals has arisen in succession from the highest race developed up to that 

 time. 



Further, as the leading motif of the whole course of this solution he dis- 

 cerned the orderly sequence in the development of the central nervous system, 

 18618°— SM 1915 34 



