'SFXT. 123.] NERVOUS SYSTEM. 253 



in the spinal ganglia, only tliey arc, on an average, smaller, ranging 



from o'oo6'" to o - Oi8'" in diameter, the mean being from o"oo8'" to 



o - oi'", less deeply coloured Fig. rod. 



with pigment, or even co- ^ , ^ 



lonrlcss, and generally rather 



uniformly rounded. As to 



the origin of the nerve-fibres 



of the gangliated cord, it is 



especially obvious, that the 



greater part of them come 



from the rami communi- 



eantes which arise from the 



trunks of flip sninnl nprvp« From the Imman sympathetic nerve; magnified 350 



11 uilivs ui Liiu S.JJ1LWU iiei \ LS> times. A. A piece of a grey nerve, treated with 



imnipdinrplv hpvrmrl flip acetic acid; «. fine nerve-tubes; 6. nuclei of *«««*'* 



limiiLUi<uci\ UL\ OI1U. Hie fibres. B. Three ganglion-globules, one with a pale 



spinal ganglia ; they are P rocess - 



formed, in general, like the sensitive roots of these {i.e., principally 

 contain finer fibres) ; and, whether one or more from each spinal 

 nerve, are distinctly connected -with both its roots. According to 

 all that has hitherto been ascertained, the fibres of these connecting 

 branches spring principally from the spinal cord and spinal ganglia, 

 and are, consequently, roots of the sympathetic ; a smaller part of 

 them, however, may come from the sympathetic, and joining the 

 spinal nerves, be distributed with them peripherally. Having en- 

 tered the gangliated cord of the sympathetic, the rami communi- 

 cantes, in so far as they arise from the spinal nerves, almost 

 invariably divide into two or several branches, and run upwards 

 and downwards in the main cord towards its cephalic and pelvic 

 extremities; and then joining the longitudinal fibres, they all 

 gradually pass off into the peripheral branches. 



Besides the finer and thicker fibres of the rami communicant es, 

 the cord of the sympathetic contains other very numerous dark- 

 bordered, but pale, fine nerve-tubes, of o - ooi2'" to 0002" in dia- 

 meter, concerning which I unhesitatingly assert that they arise in 

 it, and are not merely continuations of the fibres of the rami com- 

 municantes, as has been lately supposed, since the discovery of 

 bipolar ganglion-globules in fish. According to all that I have 

 seen in mammalia and in man, the sympathetic ganglia agree with 

 those of the spinal nerves in so far, that they contain chiefly uni- 

 polar, more rarely bipolar cells; they differ, however, in this 

 respect, that apolar cells are certainly present in them in larger 

 quantity, and that their ganglionic fibres are invariably the finest 

 which are met with in peripheral nerves, and probably, in most 



