INNERVATION OF THE RESPIRATORY MOVEMENTS. 



613 



experience, since everyone must have noticed that the respiratory 



movements are readily affected by strong stimulation of the cutane- 



ous nerves a dash of cold water, 



for example as well as through 



the nerves of sight and hearing. 



In addition, emotional states are 



apt to be accompanied by notice- 



able changes in the respirations, 



and corresponding to this fact 



experiment shows that stimula- 



tion of certain portions of the cor- 



tex and midbrain gives distinct 



effects upon the respiratory cen- 



ter. We must assume, therefore, 



that this center is in connection 



with the sensory fibers of per- 



haps all of the cranial and spinal 



nerves, and is influenced also by 



intracentral paths passing from 



cerebrum to medulla, paths which 



are efferent as regards the cere- 



hmrn hut affprAnt ac rAo-orrJc fVio 

 >nim, DUt anerent as regards tne 



medulla. As stated above, the 

 effect of these sensory nerves 

 upon the activity of the respiratory center is varied ; the rate may 



Fig. 24>7 - To show the augmenta- 

 t ion of the respiratory movements caused 



nerve ' Ex " 



Fig. 248. To show the inhibition of the respiratory movements in a rabbit due to 

 stimulation of the central end of the vagus. The respiratory movements in this case, 

 before and after stimulation, were forced, owing to the fact that both vagi were cut. 



be changed together with an increased or decreased amplitude, the 

 inspirations and expirations may each be increased, or one phase 



