276 F. W. CARPENTER AND J. L. CONEL 



On the whole, then, the study of the Nissl bodies of autonomic 

 ganghon cells in the rabbit has tended to convince us that, as 

 far as these constituents are concerned, only one type of cell ex- 

 ists. If this means that the cells are all alike functionally, then, 

 as pointed out above, it must be the motor type that is present. 



The sympathetic cells of a number of other rodents were ex- 

 amined by the Nissl method, and found to present much the same 

 appearance in respect to the chromatophile bodies as those of the 

 rabbit. The peripheral arrangement of the flakes was a nearly 

 constant feature, and enabled the observer to identify the cells 

 at a glance as sympathetic. The material for this comparative 

 study was obtained from the trunk autonomic ganglia of the rat, 

 mouse, thirteen-lined spermophile, prairie dog, muskrat, guinea- 

 pig and porcupine. 



Although it has no direct bearing on the matter in hand, the 

 binucleate condition of many of the rabbit's sympathetic cells 

 offers some features of interest. Throughout the vertebral and 

 prevertebral ganglia of the sympathetic division of the auto- 

 nomic system cells with two nuclei (figs. 15 to 18) occur in great 

 abundance. In the peripheral ganglia situated in the wall of the 

 digestive tube (submucous and myenteric plexuses) we have not 

 observed such cells; neither have we found them in the cranial 

 autonomic ganglia (ciliary, sphenopalatine, otic). Our obser- 

 vations in regard to their presence, or rather absence, in the 

 cranial region are in general accord with those of Apolant ('96). 

 In order to ascertain the position of the dividing line between the 

 binucleate cells of the trunk and the uninucleate cells of the head, 

 we made preparations of the superior cervical ganglion and of the 

 plexus arising from it anteriorly around the internal carotid 

 artery. Many of the cells of the superior cervical ganglion show 

 two nuclei each, but as soon as the carotid plexus is reached the 

 ganglion cells scattered in it appear to be exclusively uninu- 

 cleate, thus conforming to the type of the more compact auto- 

 nomic ganglia of the head region, such as the ciliary, otic and 

 sphenopalatine. The loose sympathetic ganglia of the orbit, de- 

 scribed by Peschel ('93), also failed to show cells with two nuclei. 

 Langley's separation of the autonomic system into cranial and 



