MO TOR FUNCTIONS OF THORA CICO-L UMBAR UTFLO W 3 7 



(i) that these nerves belong to the sympathetic system, and (2) 

 that their connector fibres are in anterior roots. 



Strictly speaking, the nerves which cause secretion of sweat 

 ought to be left until I come to discuss the glandular nerves ; 

 they must, however, be introduced in this place as well, because 

 the secretion of sweat is partly due to the contraction of a layer 

 of unstriped muscle fibres, which surround the sweat glands and 

 by their contraction squeeze the sweat out of the gland. The 

 action of these muscles must be included when secretion of sweat 

 is caused by the stimulation of a nerve. The evidence given 

 by various observers, especially Langley, shows clearly that the 

 connector fibres to the motor neurons supplying the sweat glands 

 in the feet of both dog and cat invariably leave the spinal cord 

 in the thoracico-lumbar outflow. Cases of section of the cervical 

 sympathetic nerve in the human being show also that the same 

 is true for the motor neurons supplying the sweat glands in the 

 face and forehead. 



ORIGIN OF THE NERVES WHICH ARE MOTOR TO THE MUSCLES OF THE SWEAT 



GLANDS IN THE CAT. 



Situation of Glands. 



Situation of Motor Ganglion Cells. 



Roots Containing Connector Fibres 

 to these Cells. 



Fore foot 

 Hind foot 



Ganglion Stellatum 



6, 7, Lumbar 

 i, 2, Sacral 



4, 5. 6, 7, 8, 9, 10, Thoracic. 



Max. 6, 7, 8 

 12, 13, Thoracic, i, 2, 3, Lumbar. 



Max. i, 2, 3 



3. The pilomotor and skin motor nerves. In a paper published 

 by Schiff in 1870 on the autonomy of the sympathetic, the 

 author argued that the sympathetic nervous system was not an 

 independent system, but was a part of the cerebro-spinal system, 

 and based his conclusions largely upon his discovery of the pilo- 

 motor nervous system. He described the erection of hairs on the 

 tail of the cat. This observation of Schiff remained isolated and 

 indeed forgotten, until Sherrington noticed the same phenomenon 

 in the monkey, and conjointly with Langley pointed out the 

 nature of the phenomenon in the monkey and cat. 



Since this paper, Langley has worked out the details of this 

 innervation very fully, and has also shown that the same laws 

 apply to the erection of the feathers in birds, and to the move- 

 ment of the spines of the hedgehog. The main results of his 



