484 SPECIAL HISTOLOGY. 



heart, at the root of the lungs and in the lungs, on the supra- 

 renal capsules, in the lymphatic glands, in the kidneys of Man 

 occasionally, on the posterior wall of the bladder, in the mus- 

 cular 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 con- 

 ditions 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 dis- 

 played, viz. in the septum of the heart in the Frog (fig. 163), 

 ^. , , where R. Wagner has also described their 



Fipr. loo. 



occurrence. These ganglia, therefore, are 

 also sources of nerve-fibres, and the emer- 

 gent 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 satisfac- 

 torily 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 Bombinator, 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 ganglia, are disposed in their ultimate distribu- 

 tion, is as yet very doubtful. Many peripheral branches 

 anastomose with other nerves, and thus escape all further re- 

 search, as the nn. carotici externi and internus, the latter of 

 which, containing scarcely anything but fine fibres and nume- 

 rous 'fibres of Remak/ I do not look upon in the common sense 

 as a root, but as a branch, arising from the superior cervical 

 ganglion, and probably the other cervical ganglia ; as well as 



Fig. 163. Nerve-cells from the cardiac ganglia of the Frog, x 350 diam.; one 

 ■with the origin of a nerve-tube. 



