THE NERVOUS SYSTEM. 493 



with a simultaneous extinction of the nervous activity. The 

 nerve-fibres generally become yellowish, soft, laccrablc, and 

 lose their transversely banded and glistening aspect. They 

 no longer present any trace of a double contour, their me- 

 dullary substance is wholly coagulated, and their breadth 

 frequently very various (Stannius in Mull. ' Arch.,' 18 17, 

 p. 452). Whether the axis-fibres undergo change, we are, 

 unfortunately, not informed. According to Brown-Sequard, 

 incised wounds, even of the spinal-cord, in the Rabbit, united. 

 Hypertrophies of the nerve-substance itself are unknown, 

 although probably such a condition occurs in the neurilemma. 

 Virchow noticed a new formation of fine nerves in pleuritic 

 and peritoneal adhesions, and, according to the same observer, 

 it would appear that grey nerve-substance may be formed on 

 the walls of the cerebral ventricles.] 



§ 127. 



With respect to the functions of the nervous system, the 

 following remarks which are immediately pertinent to the 

 anatomical facts — may suffice. As regards the two elementary 

 portions of the nervous system, anatomical investigation shows, 

 that all its divisions, which preside over the higher functions, 

 contain grey substance in greater or less quantity, as in the 

 sympathetic, the ganglia of the spinal and cerebral nerves, and 

 in the spinal cord and brain ; whilst the nerves, which act only 

 as a conducting apparatus, contain nothing but nerve-fibres. 

 This being admitted to be the attribute of the grey substance, 

 it may further be inquired whether it presents differences 

 in its structure, as it does in its functions. With respect to 

 this I would remark as follows : the largest nerve-cells are 

 met with iu situations from which motory effects proceed, as in 

 the anterior horns of the spinal cord, amongst the fibres of the 

 anterior roots, in the medulla oblongata, at the points of origin 

 of the motor cerebral nerves, in the cortical substance of the 

 cerebellum, the pons Varolii, and crura cerebri ; whilst the 

 smallest cells are found in the sensitive regions, as in the pos- 

 terior horns of the spinal cord, the corpora restiformia, and 

 quadrigemina. There does not however, appear to be any con- 

 stant relation between the size of the cells and the existence of 

 sensitive or motor functions, for, in the ganglia of the ccrcbro- 



