I06 HUNTER. [Vol. II. 



another, as Bethe holds, and not that it is an exhibition of ana- 

 tomical difference between motor and sensory roots, as Apathy- 

 seems to believe. In many cases the sheath does not stain, 

 and the fibrils appear to be loose in a non-staining perifibrillar 

 substance. In such conditions they are usually grouped into 

 small bundles of from two or three to a dozen fibrils. In thick 

 sections the characteristic wavy course of the fibrils, as de- 

 scribed by Apathy, Bethe, and others, can be seen. No heavy 

 connective-tissue sheath is found surrounding the smaller nerve 

 trunks. There is, however, a thin connective-tissue sheath 

 about some of the smaller nerves, which, in the main nerve 

 trunks, becomes quite noticeable, and forms a decided capsular 

 sheath around the ganglion. 



In the central nervous system the conditions are more diffi- 

 cult to make out. The structure seen could be best explained 

 by the elementary network of Apathy or the anastomosis of 

 Bethe. The sheath appears to be lost, and the interior of the 

 ganglion (neuropile of authors) seems to be made up of fibers 

 of different sizes, crossing and recrossing each other. These 

 fibers are frequently seen to branch or divide dichotomously, 

 but no clear cases of anastomoses have been made out. This 

 is difficult because of the widely different courses taken by 

 fibrils in the ganglion. Intermingled with the nerve fibrils and 

 almost indistinguishable from them are the so-called neuroglia 

 fibers. Neuroglia nuclei are scattered through the ganglion as 

 well as through the nerve trunks. Whether the fibrils just 

 described are homologous with the primitive fibrils of Apathy 

 and Bethe, the author is not prepared to say without further 

 research. Such, however, seems to be the case. 



One interesting fact with regard to a comparison of my re- 

 sults with those of Nansen, who worked on the nerve tube of 

 Ascidians (see Nansen, Pis. XXI, XXII), might be given here. 

 It was observed that the nerve trunks, as well as the central 

 ganglion fiber mass, when treated with chromic mixtures such 

 as Nansen used, gave results much like those exhibited in his 

 plates. The shrinkage caused by the chromic acid gave the 

 nervous tissue the appearance of a number of tubes. If, 

 however, these so-called tubes were followed to the ganglion 



