40 NERVOUS SYSTEM. 



In the digestive apparatus^ it furnishes sensibility to the 

 pharynx, oesophagus, and stomach, as well as motion to these 

 same parts, and perhaps, also, to the small intestine. 



[According to Legros and Onimus, electrization of the 

 pneumo-gastric, with interrupted currents (faradization), 

 arrests intestinal movements, and arrests these not in a state 

 of contraction but of relaxation.] 



Finally, it presides over the secretion of the glands of 

 the trachea and bronchi, and perhaps, also, the glands of 

 the stomach ; however, in this connection, the experi- 

 ments are contradictory and even less conclusive concern- 

 ing these last-named points; the same holds true with 

 regard to the formation of sugar in the liver ; these fibres, 

 according to Cl. Bernard, seem to be centripetal ; by means 

 of their peripheral extremities located in the lungs they would 

 excite reflexively those nerves tending to the formation of 

 sugar (vaso-motor? ). 



Spinal Accessory Nerve. This, considered by Bischoffand 

 Longet as accessory (motoiy portion) to the pneumo-gastric, 

 is, in a physiological point of view, the especial antagonist of 

 the pneumo-gastric, since it presides over the movements of 

 phonation, almost all of which are opposed to the respiratory 

 movements, strictly speaking, as well in the glottis (internal 

 branch of the spinal nerve) as in the thorax (external 

 branch) (Cl. Bernard). Special indications are also found 

 in the study of phonation, which lead to the consideration of 

 the spinal as a nerve of phonation and of mimicry. 



Hypoglossal (9th pair). This is exclusively a motory 

 nerve for the tongue and hyoid muscles. When this nerve 

 is cut in a dog, the animal can no longer move his tongue, 

 which hangs out between the teeth ; he bites the tongue when 

 moving the jaws, and seems to feel acute pain from the 

 wounds, but is powerless to withdraw the tongue behind the 

 dental arches. 



2. Spinal Nerves. The thirty-one pairs of nerves given off 

 from the spinal cord form mixed roots, and contain an inex- 

 tricable mixture of centripetal and centrifugal nerves ; how- 

 ever, these two elements, so opposing in character, are for a 

 short distance separated, and called by the name of the spinal 

 roots. 



The anterior roots (Fig. 13, A, A, A) contain centrifugal 

 fibres, that is to say, secretory and motor nerves, destined as 

 much for the striated as for the smooth muscles (among 

 others, the vaso-motor apparatus). 



