No. I.] SYMPATHETIC GANGLIA OF VERTEBRATES. 45 



these neurons is very irregular; the neuraxis, a, which in the 

 cells sketched could be traced for a long distance as an exceed- 

 ingly fine fiber, was lost in the network of Auerbach's plexus. 

 The dendrites, b, have a very irregular, jagged appearance, 

 perhaps better shown in the figure than can be described. 

 Such multipolar cells were seen only in the intestinal canal ; in 

 all other sympathetic ganglia of the frog known to me the cells 

 are unipolar. 



Pericellular Network and Spiral Fiber. — In well-stained meth- 

 ylene blue preparations of any sympathetic ganglion of a frog it 

 may be seen that the cell body of each neuron constituting said 

 ganglion is enclosed in a pericellular network or plexus. In 

 such preparations, double-stained in alum carmine, it may 

 readily be seen that this network is intra-capsular (see PI. Ill, 

 Figs. 9 and 10, c, capsule of cells), and is in contiguity with the 

 enclosed cell body, but never continuous with it. The arrange- 

 ment and structure of the fibrillae constituting the network are 

 very variable, as may be seen from PI. Ill, Figs. 8-10. The 

 fibrillae may be very loosely or more densely woven ; their 

 arrangement seems largely accidental. The fibrillae may be 

 smooth or varicose. This apparent difference in structure 

 seems to depend somewhat on the length of time the tissues 

 are exposed to the air before fixing them. It will be remem- 

 bered that with this method the nerve tissues are usually almost 

 colorless about one hour after the injection, the interval of time 

 allowed to elapse before the ganglia are exposed ; if, on exposing 

 the ganglion to the air, they become blue in a few moments, as 

 they often do, the fibrillae of the network have a much smoother 

 appearance than when it is necessary to expose them ten, fifteen, 

 or even twenty minutes before the stain has developed, in which 

 case the fibrillae usually present a very varicose appearance. 

 Now and then quite large nodular masses, stained deeply blue, 

 may be seen at some nodal points in the pericellular network, 

 d, of PI. Ill, Figs. 8 and 9; Retzius (21) has also described 

 such nodular enlargements. The question as to whether the 

 network is an open one, as described by Ehrlich (18), Aronson 

 (19), and Lawdowsky (22), or a closed one, — Arnstein (20), 

 Smirnow (24), and Feist (23), — has, I believe, been most cor- 



