No. I.] SYMPATHETIC GANGLIA OF VERTEBRATES. 63 



2) In frontal sections of chick embryos of the fifteenth day 

 it was seen that some of the neuraxes passed up or down in the 

 ramus internodalis, and entered one of the contiguous ganglia. 



3) Many of the neuraxes take a peripheral course in the ven- 

 tral branch of the spinal nerve of the segment. 



Both Cajal and Lenhossek were able to trace cerebro- 

 spinal nerve fibers into the sympathetic ganglia of the chick. 

 The latter describes these as coming from the ventral ramus 

 of the spinal nerve, as branching in the ganglia, and as termi- 

 nating in a "free ending." Cajal was able to trace such fibers 

 to the anterior root, while Lenhossek is inclined to regard them 

 as coming from the posterior root. Neither of these investi- 

 gators describes pericellular plexuses in the sympathetic ganglia 

 of birds. 



The results obtained by me with the methylene blue method 

 confirm in many particulars the observations made by Cajal 

 and Lenhossek with the Golgi method. I also find the sympa- 

 thetic neurons multipolar, with numerous dendrites and one 

 neuraxis. The body of such neurons may be irregularly round 

 or oval, or of a triangular shape. In ganglia stained in meth- 

 ylene blue, and in those so stained and fixed in ammonium 

 molybdate and sectioned, chromophile granules may be seen 

 in the protoplasm of the ganglion cell, if the staining is not 

 too intense or diffuse, as is often the case. These granules are 

 very fine and evenly distributed through the protoplasm, as 

 (PI. V, Fig. 21) a portion of a section of one of the ganglia of 

 the dorsal sympathetic chain may show. 



The dendrites, as Lenhossek has correctly stated, are short 

 and thick and not prone to much branching. They form an 

 interlacing network between the cell bodies of the ganglion 

 cells. As the cell bodies of such cells are surrounded with 

 a nucleated capsule (see c of Fig. 22), this dendritic plexus is 

 extra-capsular. 



Cajal mentions this arrangement of the dendrites, formed by 

 the "short process," and describes it as pericellular nests — 

 "nido pericellular." He further suggests that through such 

 pericellular nests ganglion cells may be physiologically asso- 

 ciated. 



