424 SPECIAL HISTOLOGY. 



in the nerves of the impregnated uterus (" Darmnervensjst.," p. 30) 

 in very great quantity, so that they amount to from three to ten times 

 the number of the dark-bordered true nerve-fibres. Thev constitute 

 the main part of the proper basis of these trunks, and the dark-bor- 

 dered tubes extend through them, sometimes more isolated, sometimes 

 assembled in larger or smaller fasciculi ; more rarely, and only in the 

 neighborhood of the ganglia themselves, do they appear to form sheaths 

 to individual tubes of the finest kind. Besides these " fibres of Remak," 

 the peripheral ramifications of the sympathetic are, above all, distin- 

 guished by a great number of ganglia. These bodies, of a larger or less 

 size, some even microscopic, are placed on the branches or terminations, 

 and, indeed, the microscopic ganglia, so far as is hitherto known, on the 

 nervi carotid, in the pharyngeal plexus, in the heart, at the root of the 

 lungs and in the lungs, on the suprarenal capsules, in the lymphatic 

 glands, in the kidneys of Man occasionally, on the posterior wall of the 

 bladder, in the muscular substance of the neck of the uterus in the 

 Sow, in the plexus cavernosi, and with respect to their distribution, will 

 be further adverted to when we come to speak of the viscera. I will 

 here remark in general^ concerning them that with respect to the size 

 and figure of the nerve-cells, and the origination of fine fibres, they 

 present precisely the same conditions as the ganglia of the main trunk. 

 As regards the last point, it may be especially noticed, that in one situa- 

 tion the origin of nerve-fibres from unipolar cells, and the rarity of the 

 double origin of fibres, is particularly well displayed, viz. in the septum 

 of the heart in the Frog (Fig. 163), where R. Wagner has also described 

 their occurrence. These gano-lia, therefore, are also 

 sources of nerve-fibres, and the emergent branches 

 always contain more than the roots, on the supposition 

 that the fibres come out only in one direction, which 

 perhaps in most places may be the case. In the same 

 situation also, it is most readily and satisfactorily 

 seen that many of the cells are apolar and without 

 any processes (Fig. 163); as is also most plainly shown 

 in the cardiac ganglia and small ganglia, on the wall 

 of the urinary bladder in Bomhinator, in which ganglia, as well as in 

 the similar ganglia in the Frog, the conditions described are as manifest 

 as possible. 



How the fibres arising from these various localities, from the rami 

 communicantes, the ganglia of the main trunk, and the peripheral gan- 

 glia, are disposed in their ultimate distribution, is as yet very doubtful. 

 Many peripheral branches anastomose with other, nerves, and thus escape 

 all further research, as the nn. carotid extcrni and internus, the latter 

 of which, containing scarcely anything but fine fibres and numerous 



Fig. 163. — Nerve-cells from the cardiac ganglia of the Frog, magnified 350 diam.: one 

 with the origin of a nerve-tube. 



