GANGLION CELLS IN THE SYMPATHETIC SYSTEM 273 



peripheral neurones of the cerebro-spinal system, and appears to 

 have been Dogiel's idea when he WTote his account of the two types 

 under consideration. 



In our silver-nitrate material, which probably shows a more 

 complete picture of the cellular elements of a single ganglion 

 than has been obtained with methylene blue, neurones interme- 

 diate in structure between the two extremes described above are 

 of frequent occurrence. Cells may be selected so as to form a 

 series showing a gradual transition from one type to the other. If 

 we start with the so-called sensory type, we may see in this series 

 a slight but constant increase in the size and branching of the 

 dendrites until the other extreme is reached, the so-called motor 

 type. Cells from such a series are represented in figures 3 to 8. 

 If we accept Dogiel's classification, it is quite impossible to assign 

 those neurones that occupy intermediate positions to either his 

 motor or his sensory group. Since, then, the two types are not 

 sharply separated by morphological characters, but are, on the 

 contrary, connected by intermediate forms, they are probably 

 to be looked upon as extreme examples of the variation existing 

 among the sympathetic ganglion cells, all of which may very 

 possibly be of one function, i.e., motor. This follows from the fact 

 that it is the presence of the sensory type only that is open to 

 question. The morphological differences among the neurones 

 are conceivably due, as other writers have suggested, to a cor- 

 relation with differences in the kinds of tissues innervated by 

 them. 



SYMPATHETIC GANGLION CELLS OF THE RABBIT (NISSL METHOD) 



The attempt to separate sympathetic cells into two precise 

 groups having proved negative when attention was directed to 

 their external morphology, we next undertook a study of the 

 chromatophile substance of the cell-bodies to see if the separa- 

 tion might be effected on the basis of differences in internal 

 structure. Here, again, we have in the cerebro-spinal system of 

 nerves constant and well-defined internal characters which sharply 

 mark off the sensory from the motor neurones. A glance at fig- 



