THE NERVOUS SYSTEM. 423 



termed sympathetic fibres. From these facts it would appear certainly 

 evident, that it is impossible to regard the fine fibres of the sympathetic 

 as altogether of a special nature, and peculiar to it alone, and that it 

 will not do, in the anatomical point of view, to classify the fibres accord- 

 ing to their size, very many in fact, in their course, assuming all possi- 

 ble degrees of thickness. Allowing that the great number of very fine 

 pale fibres in the sympathetic is a prominent anatomical fact, as is also 

 indeed the case in the higher nerves of sense and in the gray substance, 

 still, speaking physiologically, I am by no means of opinion that the 

 fineness of the fibres in the sympathetic indicates anything of a special 

 nature in them, and which does not exist elsewhere, but perhaps, that 

 where this condition does exist both in them and in other situations, it 

 is connected with a distinct kind of function. 



125. Peripheral distribution of the ganglionic Nerves. From the 

 main trunk of the sympathetic arise the branches proceeding to the 

 periphery, which without exception, receive finer and thick fibres from 

 it, but besides these, in part at least, contain other special elements, to 

 which is due their varied aspect. Some of them, for instance, are 

 white, as is the main trunk in most situations, such are the n. splanch- 

 nici ; others grayish white, as the nervi intestinales, the nerves of the 

 unimpregnated uterus (Remak, "Darmnerven System," p. 30); others 

 again gray, and at the same time less firm to the feel, as the n. caroti- 

 cus, internus, the nn. carotid externi s. molles, the nn. cardiaci, the 

 vascular branches in general, the branches connecting the large ganglia 

 and plexuses in the abdomen, those which enter the glands, and the 

 pelvic plexuses. The peculiar condition of the latter nerves depends, 

 in part, upon the paler color of the fine fibres of the sympathetic itself, 

 but in great measure upon the presence of the fibres, named after their 

 discoverer, the fibres of Remak ("gelatinous fibres " of Henle), which 

 were at first regarded as a kind of nerve-tubes, and of which, even now, 

 some cannot be convinced that they are only a sort of connective tissue. 

 They are sometimes more readily isolated, sometimes more united into 

 a compact substance resembling homogeneous connective tissue. In the 

 former case they present the aspect of flat, pale fibres, 0*0015-0-0025 

 of a line broad, and 0-0006 of a line thick, of an indistinctly striated, 

 granular, or more homogeneous substance ; and which, under the action 

 of dilute organic acids, exhibit precisely the same conditions as connec- 

 tive tissue, and from point to point are furnished with, mostly elongated, 

 or fusiform nuclei, 0-003-0-007 of a line long, 0-002-0-003 of a line 

 broad. These fibres, again, are found in almost all the gray portions 

 of the ganglionic nerves I cannot find them in many parts of the 

 pelvic plexuses in Man, where they are replaced by a non-nucleated 

 abundant connective tissue, though they are said by Remak to abound 



