ix THE SKIN AND CUTANEOUS GLANDS 497 



was not inhibited by ligation of the aorta, but did cease, as in 

 other glands, after atropinisation of the animal. 



Luchsinger (1877) and Nawrocki (1878) confirmed the existence 

 of sudoriferous fibres in the abdominal sympathetic for the pro- 

 duction of sweat in the cat's hind-foot, and also found sudoriferous 

 fibres in the thoracic-sympathetic to the front paw of this animal, 

 and in the cervical sympathetic to the head of the pig and horse. 



The spinal origin of these fibres has been worked out by a 

 number of observers Luchsinger, Nawrocki, Vulpian, Ott, and 

 more recently by Langley (1891). According to Langley, the 

 sudorific fibres for the cat's hind paw run from the cord to the 

 sympathetic through the rami communicantes of the last two 

 thoracic roots and the first three or four lumbar roots. They 

 connect with the last lumbar and first sacral ganglia, and run in 

 the grey rami of these ganglia to the spinal nerves which unite 

 to form the sciatic. 



The sudorific fibres to the front paw, according to Langley, 

 reach the sympathetic by the rami communicantes of the 6th, 7th, 

 and 8th thoracic nerves; then ascend to the stellate ganglion, 

 and reach the brachial plexus via the grey fibres of this ganglion, 

 and pass thence to the median and ulnar nerves. 



Besides the secretory fibres for sweat, some authors admit the 

 existence of antagonistic fibres, i.e. inhibitory to the sweat glands 

 (Vulpian, Ott, Arloing). But the experimental data adduced are 

 ambiguous, and do not prove the existence of a double order of 

 nerves for the regulation of cutaneous secretionnhe sudorific 

 fibres can be excited, and the secretion of sweat promoted, by 

 exciting the centres from which they emanate. The centres for 

 the secretory sweat fibres to the hind limbs of the cat are in the 

 lumbar cord ; those for the anterior limbs in the cervical cord. 



On separating the dorsal from the lumbar cord in the cat by 

 a cross-section, and then placing the animal for a few minutes in 

 a temperature of 40-45 C., sweating is provoked not only in the 

 pad of the anterior foot, but in the posterior as well (Luchsinger). 

 This secretion depends not only on a direct action of the super- 

 heated air upon the sudoriferous glands, but upon the activity of 

 the central nervous system. In fact, when the sciatic is previously 

 divided on one side, no sweat is secreted at the pad of the corre- 

 sponding foot, although the sweat glands here are exposed to the 

 action of heat as much as in the three other limbs. 



The sweat excited by an asphyxial condition of the blood (as 

 is probably the case with the sweat of the death-agony) depends 

 on excitation of the nerve centres, and not on that of the peripheral 

 apparatus. In fact, if a cat in which the sciatic is divided on one 

 side is asphyxiated, sweat appears only in the three paws connected 

 with the centres, and not in that which has been cut off. 



Both in warmed and in asphyxial blood sweating may be 



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