98 THE ROYAL SOCIETY OF CANADA 



in the lactic acid content of the blood, but it remains constant or in- 

 creases in two experiments in which the hyperpnœa developed acute- 

 ly (Nos. XXII and XXX) and an excess of lactic acid and a marked 

 lowering in P^ of the arterial blood is evident. Inasmuch as the acid 

 excretion in all of the normal decerebrate animals becomes markedly 

 depressed, it is significant that in those animals of the hyperpnœa 

 group the acid excretion should have continued high. 



7. Decerebrate rigidity was very marked in the four animals of 

 this series in which there was excessive hyperpnœa and was slight in 

 that (XVII) in which this was of lesser degree. This observation is 

 possibly of interest, since it suggests that the accumulation of lactic 

 acid, which was very high in two of these cases, may depend on the 

 abnormally contracted musculature. According to such a view, in 

 the state of permanent (plastic) tonus the blood supply to the muscles 

 may be inadequate to supply sufîficient oxygen to effect the oxidative 

 removal of the lactic acid which therefore accumulates and overflows 

 into the blood. With regard to the rectal temperature it will be noted 

 that this usually rose somewhat, but not sufficiently to account for 

 the dyspnœa. 



Glycosuria of slight degree was observed in two of the experi- 

 ments; sugar was not examined for in the urine of the other animals. 



It may appear that the division of the animals into two groups, 

 according to whether or not decided hyperpnœa became established, is 

 arbitrary and that certain of the observations should have been classi- 

 fied as belonging to an intermediate group. Although this is true, it 

 is nevertheless, we believe, more correct to adopt the present classi- 

 fication since it corresponds to the general impression, which is con- 

 veyed by actual experience with decerebrate animals. As a matter of 

 fact, the above records include, out of a total of twenty animals, all 

 those save one in which satisfactory spontaneous regular breathing 

 existed one hour after the decerebration. In the one exception, the 

 breathing was excessively rapid and deep, the aveolar CO2 well below 

 two per cent and the blood carbonate below twenty per cent. 

 Although the rigidity was of slight degree this animal was extremely 

 hyperexci table, the section being well forward of the anterior corpora 

 quadrigemina, and the hyperpnœa was definitely dependent upon 

 afferent stimulation induced by faulty technique in catheterization. 



In seven of the twenty animals satisfactory breathing did not 

 spontaneously return within one hour after the decerebration, and the 

 animals were discarded. It was usually the case that the section in 

 their cases was well back, but its exact position has not been recorded. 



