iv Journal of Comparative Neurology. 



sheath of the axis-cylinder process. A single nucleus is found in each 

 cell, situated in its middle. 



The cells of the sympathetic ganglia are multipolar, with three to 

 five, or even more processes. Their size varies from 20-25// to 5-6 // . 

 They are also enclosed in a capsule. The spinal and sympathetic gan- 

 glia of birds are very rich in tigroid substance. This seems equally 

 distributed through the cell-body with the exception of a narrow peri- 

 pheral zone, which in the larger spinal ganglion cells seems free from 

 this substance. 



A more careful study of the tigroid substance of the spinal ganglia 

 shows the small patches of this substance seen on more superficial ex- 

 amination, to be made up of small, deeply stained granules of variable 

 size. The tigroid is arranged in the form of a network, of which these 

 fine granules and the larger patches form the greater part. 



The tigroid appears early in the embryo. In a chick of the 4th 

 day, traces are observed ; by the 6th day, it is present in appreciable 

 quantity. It appears in the peripheral nervous system before it does in the 

 central, and seemingly first in the head-ganglia, the jugular ganglion 

 of the vagus being especially mentioned by Timofeew. In the spinal 

 ganglia, the tigroid makes its appearance as a diffuse, non-granular sub- 

 stance which fills the whole cell. As the spinal ganglion cells enlarge, 

 this substance is found as a zone in the peripheral portion of the cell, 

 leaving a tigroid-free zone in the center around the nucleus. This stage 

 seems characteristic for a great part of embryonic life. The granules 

 appear first in the tigroid-free zone, later in the whole cell, and by the 

 17th day the cells present the appearance seen in adult life. 



The ground substance, both in the spinal ganglion cells and the 

 sympathetic cells is of a fibrillar structure. 



The nuclei of both kinds of cells are surrounded by a distinct nucle- 

 ar membrane, from which fine threads, beset with granules pass into the 

 nucleus, forming a network with narrow meshes. Network and gran- 

 ules are acidophile ; two nucleoli are found, one of which is distinctly 

 acidophile, the other basophile, the latter corresponding to the large 

 nucleolus found in the nerve cells of other vertebrates. G. c. h. 



Ruffloi on Nerve Endings in tlie Skin.' 



In this monograph Ruffini gives his observations on the nerve end- 

 ings in the human skin; they were made with Fischer's gold chloride 



* Angelo Ruffini. Sulla presenza di nuove forme di terminazioni nervosa 

 nello strato papillare e subpapillare della cute dell'uomo con un contribute alio 

 studio della dei corpuscoli del Meissner. 



