No. I.] SYMPATHETIC GANGLIA OF VERTEBRATES. 75 



Pericellular plexuses, enclosing the cell body of the sympa- 

 thetic neurons of Mammalia, have been described for nearly all 

 sympathetic ganglia in all parts of the sympathetic system ; in 

 the cranial sympathetic ganglia as follows : Ciliary ganglia by 

 Kolliker (32) and Michel; spheno-palatine by Lenhoss^k {29); 

 and submaxillary and sublingual by myself (45); in the larger 

 ganglia of the chain by a number of investigators, beginning 

 with Aronson (19) ; in the respiratory passages by Arnstein (46) ; 

 in the heart of the rabbit by Aronson (19) ; intestinal canal 

 and other peripheral ganglia by Dogiel ; in the suprarenal by 

 Dogiel (47) ; in the epididymis by Timofeew (48) ; and have 

 further been seen by me in the bladder and oesophagus of the 

 cat. In all the Mammalia studied, and in all the ganglia, they 

 have essentially the same structure, and so far as my observa- 

 tions go, in sections of the ganglia of the sympathetic chain and 

 various peripheral ganglia of the dog, cat, rabbit, and guinea pig, 

 the pericellular plexuses are always intra-capsular. Sometimes 

 only one fiber may end in a pericellular plexus ; sometimes two, 

 three, or even more fibers may take part in the formation of 

 one plexus ; these fibers are always, so far as may be gathered 

 from the investigations on the sympathetic ganglia of Mammalia, 

 collateral or end branches of medullated fibers. 



So far as concerns the small medullated fibers, which may 

 be traced from this or that nerve root of a ganglion into said 

 ganglion, my own observations confirm wholly the account 

 given by Dogiel (40). Such fibers may readily be seen in 

 sections of methylene blue stained ganglia, where they are 

 found branching and rebranching, and forming, with the den- 

 dritic processes of the ganglion cells, what Dogiel has described 

 as the intercellular plexus ; this plexus is always extra-capsular 

 and may be seen in PI. V, Fig. 26 — a portion of a section 

 about 20 /A in thickness. In sections one-third or one-half that 

 thickness I have now and then observed what I have looked 

 upon as the ending of the fibers under discussion. In PI. V, 

 Fig. 25, is reproduced a cell from a section about 10 yu, in thick- 

 ness of the solar ganglion of a cat stained in methylene blue. 

 The cell body of this cell was deeply stained, its neuraxis, a, 

 and dendrite, b, not so deeply ; these could, however, be clearly 



