CIRCULATION. 209 



nected with small ganglia lying as a rule near the organs to which the nerves 

 are distributed. The remaining division of lumbar fibres running downward 

 in the sympathetic chain, and including the majority of the nerve-fibres to the 

 external generative organs are connected with nerve-cells in the sacral gan- 

 glia of the sympathetic. 



The sacral group of nerves enter ganglion-cells scattered on their course, 

 most of the nerve-cells for any one organ being in ganglia near that organ. 



Bladder. — Neither lumbar nor sacral nerves send vaso-motor fibres to the 

 vessels of the bladder. 



Portal System. — It has already been said that vaso-constrictor fibres for the 

 portal vein were discovered by Mall in the splanchnic nerve. Constrictor fibres 

 have been found by Bayliss and Starling 1 in the nerve-roots from the third to 

 the eleventh dorsal inclusive. Most of the constrictor nerves pass out from 

 the fifth to the ninth dorsal. 



Back. — The dorsal branches of the lumbar and intercostal arteries, issuing 

 from the dorsal muscles to supply the skin of the back, 2 can be seen to con- 

 tract when the gray ramus of the corresponding sympathetic ganglia are 

 stimulated. 



Limbs. 3 — The vaso-motor nerves of the limbs in the dog leave the spinal 

 cord from the second dorsal to the third lumbar nerves. The area for the hind 

 limb, according to Bayliss and Bradford, is less extensive than that for the 

 fore limb, the former receiving constrictor fibres from nine roots, namely the 

 third to the eleventh dorsal, the latter from six roots, the eleventh dorsal to 

 third lumbar. Langley finds that the sympathetic constrictor and dilator 

 fibres for the fore foot are connected with nerve-cells in the ganglion stella- 

 tum ; while those for the hind foot are connected with nerve-cells in the sixth 

 and seventh lumbar, and the first, and possibly the second, sacral ganglia. 



Thompson and Bancroft have studied the nerves to the superficial veins 

 of the hind limb. The latter finds that in general the arrangement of the 

 vaso-motor nerves corresponds to that of the arterial vaso-motor nerves and 

 the sweat fibres. The fibres to the superficial veins originate from the lower 

 end (first to fourth lumbar nerves) of the region of the spinal cord supplying 

 all the vaso-motor nerves for the hind limbs. 



Tail. 4 — Stimulation of any part of the sympathetic from about the third 

 lumbar ganglion downward almost completely stops the flow of blood from 

 wounds in the tail. The vaso-motor fibres for the tail leave the cord chiefly 

 in the third and fourth lumbar nerves. Their stimulation may cause primary 

 dilatation followed by constriction. 



Muscles. — According to Gaskell, the section of the nerve belonging to 



1 Bayliss and Starling: Journal of Physiology, 1894, xvii. p. 125. 



2 Langley : Journal of Physiology, 1894, xvii. |>. 314. 



:1 Thompson : Archiv fur Physiohgie, 1893, p. 104; Wertheinier : Archives de Physiologic 

 1894, p. 724; Bancroft: American Journal of Physiology, 1898, i. p. 477 ; Bayliss and Bradford: 

 Journal of Physiology, 1894, xvi. p. 16; Langley: Journal of Physiology, 1894, xvii. p. 307; 

 Piotrowski : Archiv fur die ycsmnmfe Physiologic, 1893, lv. p. 268. 



4 Langley : Journal of Physiology, 1894, xvii. p. 311. 

 Vol. I.— 14 



