2 4 4 



NERVOUS SYSTEM. 



[SECT. 119. 



we find that the motory chief!}- contain thick fibres, whilst those 

 destined for the skin and the other above-mentioned organs have 

 finer ones, still ajl the tubes become at length uniformly fine in 

 their terminal distribution. The nerve-fibres of all the spinal 

 nerves, appear to run quite isolated and without dividing in the 

 and branches ;' towards their termination, on the other hand, 

 divisions may frequently occur, and, at least in certain animals 

 (mice, batrachian larvae), also reticular anastomoses. The ter- 

 mination itself takes place, perhaps, everywhere, by means of free 

 extremities. 



O 



§ 119. The Structure of the Spinal Ganglia is, in mammalia, 

 Fig. 100. difficult to investigate, yet I be- 



lieve I can state the following 

 with certainty. The sensitive 

 roots, as far as I have hitherto 

 been able to ascertain, enter 

 into no connection icitli the gan- 

 glionic globules in the ganglion, 

 but pass through in the form of 

 one, or in large ganglia, of nu- 

 merous anastomosing bundles, to 

 be collected again beyond the 

 ganglion, into one trunk, which 

 then immediately- mingles with 

 the motor root. The most of the 

 ganglionic globules,' perhaps all, 

 are themselves in connection, as 

 it appears, with nerve-fibres, and 

 in such a manner, that only one 

 nerve-fibre, or two, very rarely 

 several, arise from them. These 

 fibres, which I call ganglionic 

 fibres, proceed, in by far the. 



a lumbar ganglion of a young dog, treated greater part, perhaps all, in a 



with caustic soda, and magnified 45 times. ° r > r 1 > 



s. sensitive root. m. Motor roots, r, a. peripheral direction : they ioin 



Anterior branch of the spinal nerve. R, p. 1 ± > J d 



Posterior branch gr. Ganglion with the cells an( J reinforce the rOOt-fibrCS, 



and .ganglionic fibres, which reinforce the 



sensitive root. passing through the ganglion so 



that every ganglion is, accordingly, to be regarded as a source of 

 new nerve-fibres. 



For the investigation of the spinal ganglia, those of the fifth sacral and 

 coccygeal nerves of man and of the smaller mammalia maybe selected, and are 



