254 



Scientific Proceedings (121). 



Alcock, Einthoven and others that expansion of the lungs sets up 

 electrical variations in the vagus, thus showing these sensory 

 impulses actually exist. A number of years ago we 1 called atten- 

 tion to the alteration in respiration after section of the cord or 

 division of the posterior thoracic roots. That impulses are set 

 up in the joints of the thoracic cage every time the thorax expands 

 may be shown by connecting the peripheral end of a cut inter- 

 costal nerve to a string galvanometer. There is an electrical 

 variation each time the thorax is expanded. The respiratory 

 center is thus informed of the position of the thorax as well as the 

 position of the lungs. We will discuss in detail at a later time the 

 effects of these impulses on the respiratory center. 



One of the means of testing ataxic muscle is to have it do cer- 

 tain movements more strenuous than normal. The respiratory 

 mechanism may be tested in this manner with either increased 

 C0 2 or decreased 0 2 in the air. We finally adopted the method 

 of rebreathing. By this method we found animals with divided 

 vagi or with divided cord are much less efficient than normal 

 animals. In a number of cases we found in animals with divided 

 cord that rebreathing from the spirometer caused a marked slowing 

 of respiration. The respirations always increased in depth but 

 the animals were unable to make a deep and at the same time a 

 rapid respiration. In no case after division of the cord did we find 

 an increase in rate nearly proportional to that in the intact animal. 

 As examples two experiments may be quoted : 





Rate. 



Vol. 



Total c.c. 

 per Min. 





40 



61.6 



2464 





SO 



75-6 



378o = +53% 



Cord cut 7th cervical 17 min. after operation. . . 



37 



40.7 



2030 



After 1 min. rebreathing 



30 



47-6 



1628 = - 19% 





39 



50.4 



1965 





48 



75-6 



3628 = + 84% 





15 



75-6 



1134 



After 1 minute rebreathing 



15 



106.4 



1489 = +39% 



15 minutes after division of cord at 7th cervical. . 



15 



56 



840 



After 1 minute rebreathing 



15 



70 



1050 = +25% 



> Gault, C. C, and Scott, F. H., Am. J. of Physiology, 1918, xlv, 555. 



