SYMPATHETIC NERVE. 



451 



tne cervical region : the superior cervical 

 ganglion presented the aspect of a small round 

 nodule. In the cow's embryo, measuring 



Fig. 297. 



Re 



Sixth thoracic ganglion of the left side, from the sym- 

 pathetic of a Rabbit, treated with soda, and magni- 

 fied forty diameters. 



Tr, main cord of sympathetic ; Re, Re, commu- 

 nicating branches, each dividing into two portions ; 

 Spl, splanchnic nerve ; S, small nerve proceeding 

 probably to the blood-vessel ; G, ganglion-cells and 

 libres, passing into the main cord of the sympathe- 

 tic. (After Kolliker.} 



about li inches in length, I found the ganglia 

 in the cerebral and spinal nerves, as well as 

 those of the sympathetic, very distinct. The 

 superior cervical ganglion of the sympathetic 

 appeared as a small reddish grey mass, of an 

 irregularly oval form, measuring about ^'- tn 

 of an inch in its longest diameter, soft and 

 breaking clown readily. It was situated close 

 to the pneumogastric, a narrow indistinct 

 whitish line passing downwards from the 

 lower part of the ganglion to that nerve. The 

 lower cervical ganglion presented a more 

 elongated form, and appeared to be prolonged 

 into the first thoracic : the other thoracic 

 ganglia appeared as minute greyish particles 

 between the heads of the ribs, and measuring 

 about -^th of an inch in diameter. The 

 ganglia in the lumbar and sacral regions pre- 

 sented in general a more elongated form, and 

 were not so distinctly separated from one 

 another : the connecting cord, especially in 

 the sacral region, being short and thick, and 

 looking as if it were a prolongation of the one 

 ganglion into the other. None of the branches 

 which are sent inwards from the sympathetic 

 cord, nor the ganglia occurring upon them, 

 could be accurately distinguished from the 

 surrounding structures. As regards the 



ganglia occurring on the cerebral and spinal 

 nerves, they were much more distinct than 

 those of the sympathetic. The Gasserian 

 ganglion presented the form of a greyish white 

 body, situated beneath the still soft and 

 transparent dura mater : it measured about 

 y'jth of an inch in diameter, and presented an 

 irregularly oval or triangular shape. It ap- 

 peared to consist of several opaque portions, 

 separated from one another by an intermediate 

 more or less transparent substance, thus pre- 

 senting the appearance of being composed of 

 several minute lobules. The ganglia on the 

 posterior roots of the spinal nerves were also 

 very distinct : they were arranged along the 

 interior of the spinal canal, on each side, and 

 rather anteriorly towards the bodies of the 

 vertebrae, and concealed by the spinal cord. 

 They presented an oblong or oval shape, mea- 

 sured about ^th of an inch in length and 

 about g^-th in Breadth, and presented the same 

 characters in regard to colour, &c., as the 

 Gasserian ganglion. 



In embryos from seven to eight inches in 

 length, the superior cervical ganglion presents 

 the same oval shape and reddish grey appear- 

 ance as before : it is larger, however, measuring 

 about ygth of an inch in its long diameter: 

 it consists, as before, of a number of opaque 

 round or oval portions : the intermediate sub- 

 stance exists in much smaller quantity. It 

 is surrounded by a highly vascular sheath. 

 From its lower part the communicating cord 

 is seen passing downwards for a short dis- 

 tance, when it is applied to the trunk of the 

 pneumogastric. The cord presents a flat- 

 tened aspect, and is of a greyish red colour. 

 The ganglia in other regions of the body, as 

 well as the intermediate cord, are well formed, 

 and much larger than before. The first 

 sacral ganglion of either side appears to be 

 amalgamated into a single ganglion situated 

 in the medial line. 



The splanchnic nerves and solar plexus, as 

 well as its offsets, are distinctly visible. The 

 rami communicantes are also present ; so also 

 the plexus on the abdominal aorta and epi- 

 gastric plexuses. The ganglia on the cerebral 

 and spinal nerves present the same characters 

 as before, with the exception that they are 

 considerably larger. 



In embryos measuring seventeen or eighteen 

 inches in length, not only can the parts which 

 have been already mentioned be distinctly 

 seen, but also most of the peripherical branches 

 of the sympathetic. The superior cervical 

 ganglion presents, as before, a more or less 

 oval shape, and measures about ^th of an inch 

 in its long diameter. It has still the appearance 

 of being composed of a number of round or oval 

 opaque greyish- white masses : there appears, 

 however, to be very little of the intermediate 

 transparent substance present. Its sheath is 

 very vascular, and numerous vessels also pass 

 into the interior of the ganglion between its 

 lobules : it is possessed of considerable con- 

 sistence. Its branches of communication 

 with the different nerves are also distinctly 

 seen : they have a more or less greyish red ap- 



G G 2 



