ii Journal of Comparative Neurology. 



to lo. These divide near the cell into a number of varicose or smooth 

 branches, which often enter a nerve bundle, in which they may now and 

 then be traced for a long distance. In the nerve-bundles they resemble 

 varicose neuraxes. Owing to their length it was difficult to determine 

 their mode of ending. Dogiel suggests that they end either in a spe- 

 cial end-apparatus or in the nerve-trunks. He favors the former view. 

 The neuraxes of the cells arise by a cone-shaped enlargement. The 

 majority are non-medullated ; now and then one which had a sheath of 

 myelin was observed. In a number of instances the neuraxes of the 

 cells of type two could be traced into a neighboring ganglion, where 

 they seemed to terminate. 



(c). Cells of type three. The cells of type three resemble in some 

 respects those of type one, in others those of type two. The dendrites 

 are longer than found in type one, but do not pass beyond the bounds 

 of the ganglion, forming a network between the ganglion cells. The 

 neuraxes of the cells of this type are non-medullated and may often be 

 traced for long distances. Their mode of ending was not determined. 



Two kinds of nerves were found to end in the sympathetic ganglia 

 of the heart : 



1. Medullated and non-medullated fibers of various sizes, which 

 divide repeatedly and surround all elements of the ganglion in a dense 

 network, which is, however, always extra-capsular. As the capsules of 

 the ganglion cells of the heart ganglia extend on to the dendrites for a 

 distance, it may be assumed that the fibrils of this network come into 

 immediate contact with the ganglion cells which they enclose, only at 

 the ends of their dendrites. As to the origin of the nerves which thus 

 end in the heart ganglia, the following statements are made by Dogiel : 



(a). Many, possibly all, of the non-medullated fibers and a few of 

 the medullated which end in extra-capsular plexuses, are neuraxes of 

 sympathetic nerve-cells, situated in the heart. 



(b). Medullated fibers, probably also some non-medullated fibers, 

 which form extra-capsular plexuses are neuraxes of sympathetic cells 

 situated outside of the heart. 



2. Fibers of the second class are always medullated. They 

 branch frequently before reaching the ganglia and after entering them, 

 and terminate in intricate plexuses which are intra-capsular, surrounding 

 the cell bodies of the sympathetic cells. Dogiel believes that only a re- 

 latively small number of the heart-ganglion cells are thus surrounded 

 by intra-capsular plexuses, and these are mostly cells of the first type. 

 The nerve-fibers of this second class are neuraxes of cerebro-spinal 

 neurons. g. c. h. 



