THE CONTROL OP THE RESPIRATION 



351 



eter was made to record its movements on a drum, so that an accurate 

 record of the depth and frequency of the respirations was secured. Sam- 

 ples of air were removed from the bottle by ground-glass plunger syringes 

 at frequent intervals during the time that the animal was respiring into 

 the tubing. 



joe 



400 



300 



/oo 



Fig. 129. Composite curve obtained from the data on sixteen experiments, showing the re- 

 spiratory response to COa in the decerebrate cat. Abscissae = percentage of COa in the inspired 

 air. Ordinates = the percentile increase the tidal air per minute. (From R. W. Scott.) 



The results are given in the accompanying curve (Fig. 129), which shows 

 that there is a perfect correspondence between the C0 2 percentage in the 

 air of the bottle and the pulmonary ventilation. Moreover, when the 

 bottle was filled with 2 instead of air to start with, the same results 

 were obtained, showing that the C0 2 accumulation alone was responsible 

 for the hyperpnea. In these cases the percentage of 2 remaining in the 



