THE SECRETION OF SWEAT. 677 



strated by Luchsinger 1 and Nawrocki, 2 in the horse and pig by the 

 former observer, and in the pig by the latter. Both agreed that the 

 fibres reach the sweat-glands of the face by the infra-orbital branch of 

 the fifth cranial nerve, the junction being effected by branches from the 

 cavernous plexus of the sympathetic. Neither of these investigators 

 could satisfy himself of the presence of sweat-fibres in the facial nerve. 



The origin of the sudorific fibres in the spinal cord has been studied 

 by Luchsinger, Nawrocki, Vulpian, Ott, 3 and more recently by Langley. 4 



In the case of the hind-limb of the cat, according to Langley, the 

 sudorific fibres enter the sympathetic cord by the white rami communi- 

 cantes of the last two thoracic and first three or four lumbar nerves, 

 become connected with nerve-cells in the sixth and seventh lumbar, and 

 first and second sacral ganglia of the sympathetic, and leave by the 

 grey rami of these "ganglia, to enter the anterior divisions of the corre- 

 sponding spinal nerves, and so the sciatic. The first and second lumbar 

 spinal nerves seem to supply the greatest number of secretory fibres. 

 The grey ramus to the sixth lumbar nerve is found to chiefly supply the 

 sweat-glands of the inner part of the foot, that to the second sacral 

 nerve the outer part, and, in the main, the successive rami from above 

 downward supply strips of the skin of the foot from within outwards, 

 though considerable, and, in different individuals, varied overlapping of 

 fields is noted. 



In the case of the fore-limb, the same observer finds that the sweat- 

 nerves are supplied to the sympathetic chain by the fourth to the ninth 

 thoracic spinal nerves, the main outflow of fibres being usually found in 

 a nerve near the middle of the series. All these fibres run up in the 

 sympathetic cord to the ganglion stellatum, where a connection with nerve- 

 cells is effected, and by the grey rami of this ganglion reach the brachial 

 plexus, 5 and so the median and ulnar nerves for their final distribution. 



The grey rami to the sixth and seventh cervical nerves seem to chiefly 

 supply the inner part of the fore-foot, while that to the first thoracic 

 nerve chiefly supplies the outer part. 



The fibres for the face, according to Nawrocki, leave the cord by the 

 second, third, and fourth anterior roots, and run up in the cervical sym- 

 pathetic to finally reach the infra-orbital branch of the fifth cranial 

 nerve, vid the cavernous plexus. 



Vulpian 6 and Ott 7 maintained that, in addition to the sudorific fibres 

 supplied to the limbs vid the sympathetic, others are supplied directly from 

 the cord with the nerves forming the limb plexuses. The existence of such 

 fibres was denied by Nawrocki, and Langley fully confirms the statements of 

 this observer. 



Furthermore, Vulpian and Ott maintained that inhibitory fibres to the 

 sweat-glands exist, and the theory has been recently revived by Arloing. 8 



Vulpian's evidence for the existence of such fibres was, that contem- 



1 Arch.f. d. ges. Physiol., Bonn, 1880, Bd. xxii. S. 126. 



2 Centralbl. f. d. med. Wissensch., Berlin, 1880, S. 945. 



3 Compt. retwl. Acad. d. sc., Paris, 1878, tome Ixxxvi. pp. 1308 and 1434 ; Ott, Journ. 

 Physiol., Cambridge and London, 1879, vol. ii. p. 42. 



4 Ibid., 1891, vol. xii. p. 347 ; ibid., 1894, vol. xvii. p. 296. 



5 Eckhard (Arch. f. Anat., Physiol. u. wissensch. Med., Berlin, 1849, S. 427) quotes a 

 case in man where contusion of the brachial plexus led to continuous sweating of the hand 

 on the side of the injury. 



6 Loc. cit. 7 Loc. cit. 



8 Arch, dephysiol. norm, et path., Paris, 1890, Se>. 5, tome ii. p. 1 ; and 1891, Se>. 5, 

 tome iii. p. 241. 



