of the Central Nervous Sijstem in Ascidia &c. 219 



are somewhat variable in size; they are distributed through 

 the whole of the grey substance, occurring most numerously 

 in its middle parts, the parts therefore which should be re- 

 garded as belonging to the posterior liorn. These cells, with 

 their processes, are generally less strongly coloured by stain- 

 ing fluids. To regard these different colour-reactions as indi- 

 cating a constant difference from a physiological point of view, 

 such as Bellonci * thinks he has demonstrated, and such as 

 Ahlborn seems likewise inclined to assume in Petromyzon, 

 appears to me to be still doubtful. It is certainly the case that 

 the smaller cells which stain less strongly occur particularly 

 in the middle portions pertaining to the dorsal nerve-rods, and 

 therefore may be assumed to be especially sensitive ; but I 

 have also observed in the outer ventral parts similar cells 

 which emitted their nerve-processes directly to the ventral 

 nerve-rods, and as to the motor nature of which it seems to me 

 therefore, in accordance with Golgi's work, there can be but 

 little doubt ; it must, however, be admitted that the cells here 

 situated appear generally to have a tendency to become more 

 strongly coloured than those placed in the middle part. 



As regards the form of the ganglion-cells, they appear to 

 be always multipolar, with pretty strongly branched proto- 

 plasmatic processes. I have frequently been able to trace 

 these, with their ramifications, into the white substance ; but 

 whether they extend quite to the periphery of the spinal cord 

 I have not hitherto been able to make out, although I believe 

 I have often observed it. This is a point which it may be of 

 interest, in connexion with the significance of these processes, 

 to have cleared up ; if the function of these processes be, as 

 Golgi thinks and as seems to me probable, exclusively 

 nutritive, we have here in Myxine the remarkable fact that 

 no vascular system is present in the spinal cord. 



I have only been able partially to trace the nervous pro- 

 cesses ; the processes especially which run to the ventral nerve- 

 rods, and pass directly over to form the axis-cylinder, have 

 been the easiest to observe ; these processes therefore appear 

 perfectly to agree with what Grolgi has described, and, at any 

 rate, to belong chiefly to " the anterior horn " and the ventral 

 nerve-rods ; nevertheless I believe that, as above stated, I 

 have quite exceptionally observed similar ones in the posterior 

 horn running: to the dorsal nerve-rods. As a rule I have 



* "Ricerclie intorno all'intima tessitura del cervello dei Teleostei," in 

 Atti d. R. Accad. d. Liucei, a. 270, 1878 (1879) ; and " Ricerche poni- 

 parativa sui ceutri nervosi dei Vertebrati," in Atti d. R. Accad. d. Lincei, 

 A. 277, 1879 (1880). 



15* 



