No. I.] SYMPATHETIC GANGLIA OF VERTEBRATES. 59 



plexuses above described are the endings in the sympathetic 

 ganglia of Reptilia of cerebro-spinal fibers may briefly be stated 

 as follows : 



a) The medullated fibers in the sympathetic ganglia may, 

 from their size and structure, be regarded as fibers of cerebro- 

 spinal origin. 



b) In serial sections of well-stained, sympathetic ganglia, 

 single medullated fibers, or small bundles of such, may often 

 be traced from the white rami into the ganglia, where they 

 undergo division, or give off collateral branches, and may now 

 and then, as shown in PI. IV, Fig. 17, be traced into a spiral 

 fiber and pericellular plexus. 



c) The small dorsal sympathetic ganglia of the Reptilia inves- 

 tigated are in close apposition to the spinal ganglia. By remov- 

 ing the bodies of the vertebrae, the spinal cord, with the roots 

 of the spinal nerves, the spinal and sympathetic ganglia may 

 easily be exposed. After exposing the structures as above indi- 

 cated, I have, in a large number of experiments, divided the 

 roots of the spinal nerves close to the spinal cord, and removed 

 these with the spinal and sympathetic ganglia, with short seg- 

 ments of the nerves uniting the sympathetic ganglion to the 

 sympathetic chain, and with a short portion of the spinal nerve. 

 The tissues so removed were then fixed in ammonium molyb- 

 date, imbedded in paraffin, and cut in serial sections. As a 

 rule, in the sections so obtained only a few of the nerve fibers 

 and nerve cells were well stained in methylene blue. In some 

 series, however, the staining was such that small bundles of 

 medullated fibers could be traced from the anterior root into 

 the sympathetic ganglion. The writer (26) has already drawn 

 attention to the fact that in the dorsal spinal ganglia of Reptilia, 

 stained in methylene blue, a small group of multipolar cells was 

 found within the connective tissue capsule of the spinal ganglion. 

 This group of multipolar cells is found on the ventral side of 

 the ganglion, immediately under the capsule of the ganglion, 

 and separated from the sensory cells by a connective tissue 

 septum. Into this group of cells, which, by reason of their 

 shape and structure, are looked upon as sympathetic cells, I 

 have several times been able to trace medullated fibers comingf 



