480 SPECIAL HISTOLOGY. 



occurring in the peripheral nerves, and probably in most cases, 

 quit the ganglia in various directions. As for a topographical 

 tracing of the various fibres in the main trunk of the sympa- 

 thetic, with reference to their origin from particular rami com- 

 municantes and ganglia, and their continuation into particular 

 peripheral branches, — if more be required than what has already 

 been stated — it is not by any means at present to be thought 

 of, but must be reserved for future investigation. 



[It has been asserted, that the smaller cells in the ganglia of 

 the sympathetic are different from the larger cells in the 

 spinal ganglia, for instance ; and also that they are connected 

 only with fine nerve-tubes (Robin), but this is not correct, as 

 is apparent in part from the observations of Wagner and 

 Stannius; for we find : 1. in the ganglia of the cerebral and 

 spinal nerves of the Mammalia and of man, all intermediate 

 sizes between larger and smaller nerve-cells, and also, occasion- 

 ally, though rarely, larger cells, measuring as much as O03"' in 

 the sympathetic ganglia ; and we may also be convinced, 2. that 

 the diameter of the nerve-fibres originating in the first-named 

 ganglia, is not at all regulated by that of the cells, all their 

 ganglion-fibres being pretty nearly of the same size, and which 

 is confirmed also by the bipolar cells of Fishes, where the one 

 fibre arising from the cell is often considerably thicker than 

 the other ; in Petromyzon, according to Stannius, even six times. 

 Should it be at all supposed that the small cells are peculiar 

 to the sympathetic nerve alone, I must, as above, with respect to 

 the nerve-fibres, remark, that not to mention the ganglia of the 

 roots of the cerebral and spinal nerves, small nerve- cells also 

 occur in situations where there can be no question about the 

 sympathetic, as in the spinal cord and brain, and, — if instances 

 of the same kind in the peripheral nerves be desired — in the 

 retina and cochlea. At all events, this much is certain, that the 

 ganglia of the ganglionic system of nerves constantly present 

 smaller nerve-cells, and that the fibres arising from them are 

 of the fine kind only. 



Bidder and Volkmann have shown, in the Frog, that the 

 greater part of the fibres of the rami communicantes are dis- 

 tributed peripherally, with the spinal nerves, and that only a 

 small portion of them, which moreover are derived from the 



