94 THE ROYAL SOCIETY OF CANADA 



the lactic acid content of cat's blood even under approximately normal 

 conditions. Partial asphyxiation, due to the ether, may explain the 

 variability. 



7. Other occasional observations included testing the urine for 

 sugar, the extent of muscular rigidity, and the arterial blood pressure. 

 Glycosuria, when tested for, did not appear so frequently in the cats 

 of this group as in those of the second group. On account of dilîh- 

 culties with clotting, to which the blood of many decerebrate animals 

 appears to be very prone, and because of lack of assistance, it was 

 impracticable to secure many records of arterial blood pressure. In 

 about five hours after decerebration in Cat No. XVIII, however, it 

 was 70 mm. Hg., and from the ease with which the blood flowed from 

 the femoral artery for the lactic acid estimation, it must have been at 

 this height, at least, in the case of the other experiments. 



The degree of decerebrate rigidity varied considerably in the differ- 

 ent preparations. 



A typical observation of the group of animals in which hyper- 

 pnœa developed is given in Table IV : 



In all of the animals of this group the decerebration was per- 

 formed well forward of the anterior corpora quadrigemina and the 

 decerebrated animal was very excitable, hyperpnœa being induced 

 by the slightest disturbance. As a rule this hyperpnœa was transient 

 (cf. Exp. XXII) and in all the animals the respirations progressively 

 increased in volume and rate without any evident afferent stimulation. 

 In the most extreme cases (Nos. X, XXX and XXXI) death occurred 

 in about two hours after decerebration, being usually preceded by 

 vomiting movements and convulsions. The rapid development of 

 these conditions made it impossible to analyse many samples of alveo- 

 lar air or blood for CO2, so that attention was rather given to securing 

 samples of blood and urine of adequate size so that lactic acid, H-ion 

 concentration and the acid excretion might be ascertained. The fol- 

 lowing observations are noteworthy: 



1. If we take the average minute volume of respired air of a 

 normal decerebrate cat as 1000 cc. (cf. R. W. Scott, Am. Journ. 

 Physiol., 1917, XLIII, p. 169), it is seen that in about one hour after 

 decerebration all the animals of this group were respiring normally, 

 although usually somewhat rapidly, the average for normal animals 

 being 20-25 per minute. The hyperpnœa which subsequently de- 

 veloped either did so gradually (Nos. XVII and XXII) or, after doing 

 so for a time, suddenly became much more pronounced (XXX and 

 XXXI), this type being especially prominent in hyperexci table pre- 

 parations. 



