33 DR- KLEIN. 



two sorts previously described. They are connected with the 

 more deeply situated cells. 



Finally, we have to make mention of the beautiful stellate 

 cells supplied with fine pigment-granules, which are found 

 on the nictitating membrane, especially between the cells of 

 the more superficial as well as deeper layers of the epithe- 

 lium of the outer surface. In the body of the cell (which 

 varies considerably in size), is contained an oblong or roundish 

 nucleus ; its processes are exceedingly long and abundantly 

 ramified. 



The smaller branches, which can always be clearly traced 

 by their pigment-granules, run in the cement substance be- 

 tween every two epithelial cells, forming, by junction with 

 one another and with the branches of neighbouring cells, a 

 network, the meshes of which vary in size according to the 

 abundance of the ramification, sometimes being so small as to 

 enclose only a single epithelial cell, sometimes so large as to 

 encircle a group of them. 



B. Nerves of the Peritoneum. 



In the following pages will be described the distribution 

 of nerves in the frog's mesentery and in the septum which 

 extends between the cisterna lymphatica magna and the 

 peritoneal cavity of the same animal. 



The minute nerves of the mesentery are somewhat difficult 

 to demonstrate ; the simple method of gold-tinting often fails 

 to secure the desired end. The preparations from Avhicli the 

 figures in PI. IV were taken were prepared in the following 

 manner : — A frog {Rana esculenta) was decapitated, and the 

 whole mesentery, with the intestine, cut off at its attach- 

 ments. This was then placed for an hour in a half-per-cent. 

 gold solution, and next exposed to the light in a quarter per 

 cent, solution of acetic acid till it had acquired a distinct 

 violet red colour, wdiich required four or five days. 



The mesentery was in the next place separated from the 

 intestine, and divided into several parts. These were brushed 

 off from both surfaces under water with a fine camel's-hair 

 brush, and next transferred to a watch-glass containing a 

 small quantity of not very dilute ammoniacal carmine solu- 

 tion containing an excess of ammonia, in Avhich they were 

 allowed to remain about ten minutes. After this they were 

 washed also for a few minutes in the quarter per cent, acetic 

 acid solution, and finally mounted in glycerin. The septum 

 of the cisterna lymphatica magna is prepared in precisely the 

 same manner. 



