OP THE RESPIRATORY MOVEMENTS. 515 



particularly to the face, probably perform an important part ; and in exciting 

 the first inspiration, the Fifth pair seems the principal agent. It has long been 

 a well-known fact, that the first inspiratory effort of the new-born infant is most 

 vigorously performed, when the cool external air comes into contact with the face; 

 and that impressions on the general surface, such as a slap of the hand on the 

 nates, are often effectual in exciting the first inspiratory movements, when they 

 would not otherwise commence. Dr. M. Hall relates an interesting case, in 

 which the first inspiration was delayed, simply because the face was protected by 

 the bed-clothes from the atmosphere j 1 and, on lifting up these, the infant imme- 

 diately breathed. Dr. M. Hall has also mentioned the important fact, that 

 although, if the cerebrum be removed, and the pneumogastrics divided, in a 

 young kitten, the number of acts of respiration will be reduced to four in a 

 minute, yet by directing a stream of air on the animal, or by irritating various 

 parts of the general surface, we may excite twenty or thirty acts of respiration 

 within the same space of time. He further remarks, that in the very young 

 warm-blooded animal, as in the cold-blooded animal, the phenomena of the 

 excito-motor power are far more vividly manifested than in the older and warm- 

 blooded. In the very young kitten, even when asphyxiated to insensibility, 

 every touch, contact, or slight blow, every jar of the table, any sudden impres- 

 sion of the external air, or that of a few drops of cold water, induces at once 

 energetic reflex movements, and acts of inspiration. This may be looked upon 

 as Nature's provision for the first establishment of the acts of inspiration in the 

 new-born animal. But the influence of the nerves of the general system is by 

 no means wanting in the adult ; as many familiar facts demonstrate. Every one 

 knows the fact, that the first plunge into cold water, the first descent of the streams 

 of the shower-bath, or even the dashing of a glass of cold water in the face, will 

 produce inspiratory efforts; and this fact has many important practical appli- 

 cations. Thus in the treatment of Asphyxia, whether congenital, or the result 

 of narcotic poisoning, drowning, &c., the alternate application of cold and heat 

 is found to be one of the most efficacious means of restoring the respiratory 

 movements ; and a paroxysm of hysteric laughter may be cut short by dashing 

 a glass of cold water in the face. One of Dr. Reid's experiments strikingly 

 demonstrates the variety of the provisions that have been made for the perform- 

 ance of this function. After dividing the pneumogastrics, and removing the 

 cerebrum and cerebellum, he divided the spinal cord high up in the neck, so as 

 to cut off the communication between the spinal nerves and the Medulla Oblon- 

 gata; and he found that the frequency of the respiratory movements was still 

 further diminished, although they were not even then entirely suspended ; their 

 continuance, after every channel of excitation appeared to have been cut off 

 being probably dependent (as Dr. Reid has suggested) on the circulation of im- 

 perfectly aerated blood in the Medulla Oblongata. It seems not improbable 

 that even the Sympathetic nerve, which derives many filaments from the Cere- 

 bro-Spinal system, and which especially communicates with the Pneumogastric 

 nerves, may be one of the excitors to this function ; and this, perhaps, not only 

 through its ramifications in the lungs, which are considerable, but also by its 

 distribution on the systemic vessels ; so that it may convey to the Spinal Cord 

 the impression of imperfectly-arterialized blood circulating through these, such 

 as the Pneumogastric is believed to transmit from the lungs. 



550. The Motor or " efferent" nerves concerned in the function of Respira- 

 tion, are those which Sir C. Bell has grouped together in his " respiratory sys- 

 tem." The most important of these, the Phrenic, arises from the upper part 

 of the Spinal Cord ; the Intercostals much lower down ; whilst the Facial nerve 

 and the Spinal Accessory, to the latter of which, as will be shown hereafter 



1 " New Memoir on the True Spinal Marrow," &c., p. 29. 



