502 PROCEEDINGS OF THE SOCIETY. 



taneously coiling up their arms on irritation of the oral pinnules 

 which arch over the mouth. He had experimented upon the matter in 

 various ways. Having turned out the visceral sac, he passed a needle 

 down and irritated this central organ, and immediately all the arms 

 coiled up together. Again, he turned out the visceral mass entirely, 

 thus getting rid of the centre of the ventral nerve-system, and put the 

 animal — which then consisted of a mere skeleton — into the water ; it 

 swam just as well as before, with the same beautifully co-ordinated 

 movements of its ten arms. He then tried the experiment of dividing 

 this ventral nerve, but found that it did not paralyse any of the parts 

 beyond. But when he removed the centro-dorsal cup containing the 

 central organ of what he regarded as the dorsal nervous system, the 

 whole of the arms were tetanized, from the contraction of the ligaments 

 without any muscular antagonism. He then endeavoured to cut 

 through this nerve without separating the arm ; but was unable to do 

 this successfully, as the animal threw off the arm at once. He there- 

 fore contrived to burn it away with nitric acid, and then found that 

 the arm was paralysed. 



These experiments, and the anatomical descriptions which his 

 son had given, so entirely agreed that he thought there was no 

 getting over the proof that the muscular apparatus of the arms 

 of crinoids is put in action, not by a ventral nerve-system homologous 

 with that of other Echinoderms, but by a dorsal nerve-system 

 peculiar to themselves. He thought they were perfectly conclusive ; 

 and referring to the well-known story of George Stephenson and 

 the cow, thought that if the homologists still persisted in going 

 against the facts, so much the worse for the homologists. What, 

 therefore they had to do was to ascertain exactly what was the true 

 morphology of the crinoid ; and it seemed to him that its most 

 beautiful skeleton was more like that of the Vertebrata, because it was 

 modelled upon a nervous system. The joints of the crinoidal stem, 

 and all the segments of the rays which issue from its summit are 

 penetrated by a canal for the nerve-cord ; but this canal is not found 

 in the dermal or accessory plates which constitute a large part of the 

 skeleton of many fossil crinoids. The existence of this canal became, 

 therefore, of great importance ; if it was a canal for the passage of a 

 nerve, then it became a fundamental feature in the organization of a 

 crinoid. The crinoids were exceptional also for the wonderful 

 activity of their movements ; no star-fish certainly had anything like 

 the activity or co-ordinated movements of acrir.oid. He thought, 

 then, that they ought to say that the skeleton which incloses the 

 nervous system is the fundamental basis of the crinoid ; and that 

 there was but a very imperfect analogy between it and that of the star- 

 fishes. The question afforded, to his mind, a very important lesson as 

 to not allowing theory to go against fact ; and also that microscopical 

 examination was of the greatest value in the determination of questions 

 of this kind. 



Dr. Matthews inquired what reagents were employed by Dr. P. H. 

 Carpenter in the preparation of his specimens. 



Dr. P. H. Carpenter said he had used hsematoxylin sometimes, 

 also osmic acid, or picro-carmine or borax-carmine. 



