28 



Scientific Proceedings (94). 



19 (i394) 



The spontaneous development of an acidosis condition in 

 decerebrate cats. 



By J. J. R. MACLEOD. 



[From the Physiological Department, Toronto University, Canada.] 



Investigations of the nature of the control of the respiratory 

 center are rendered difficult because of the extreme susceptibility 

 of the center to anesthetics. Much of the recent work has ac- 

 cordingly been done on man by methods suggested by Haldane 

 and his pupils, and subsequently employed by Hasselbach, Lin- 

 hard, R. G. Pearce and others. The obvious limitations to in- 

 vestigations of this type have prompted some investigators to 

 employ decerebrate animals, or those in which the medullary 

 centers are kept alive by artificial perfusion. The objections to 

 the latter type of observation are too well known to require fur- 

 ther comment here; they may or they may not be such as to render 

 the results inapplicable to the intact animal. The chief objection 

 to the use of decerebrate animals lies in the fact that the reactivity 

 of the isolated centers is uncertain. This is particularly so in the 

 case of the respiratory center. Some animals retain for several 

 hours after the decerebration, a uniform and regular respiratory 

 rate and volume, whilst others show an abnormal type of breath- 

 ing. These irregularities, apparent in the work of Porter, Means 

 and Newburgh, were also observed in the animals used by my 

 former associate, R. W. Scott, in whose experiments it was fur- 

 ther noted that apart from the animals that failed to breathe 

 properly from the start, there were others which were apparently 

 perfectly normal in this regard for some time (1-2 hrs.) after the 

 decerebration, but in which later the breathing became dyspneic 

 and irregular, and death soon followed, usually after an acute 

 attack of vomiting. 



As a preliminary to an investigation into the nature of the 

 respiratory hormone, it was considered essential to investigate 

 the cause of this delayed dyspnoea of decerebrate animals, not 

 alone because these are probably the most suitable for use in such 

 investigations, but also because the behavior of the abnormal an- 



