THE REGULATION IN HEALTH AND DISEASE 567 



lated. The composition of the alveolar air in cases of diabetic 

 coma examined by Beddard, Pembrey, and Spriggs ( 34 ) was about 

 2'2 volumes per cent, of carbon dioxide, and 17'5 volumes of 

 oxygen ; the venous blood contained only about 20 volumes per 

 cent, of carbon dioxide ; the results suggest that the hyperpncea 

 is a cause, not an effect, of the reduction of the carbon dioxide 

 in the blood, and the respiratory centre would appear to be stimu- 

 lated in some other way than by excessive carbon dioxide or want 

 of oxygen, it may be by some of the products of the abnormal 

 metabolism. Rapid ventilation of the lungs would lower the per- 

 centage of carbon dioxide in the alveolar air, and would thus 

 wash out carbon dioxide from the blood. Further observations, 

 however, are needed upon these points. 



In certain cases of heart-disease a well-marked alternation 

 of apncea and hyperpnoea was observed and described by Cheyne 

 and Stokes. The phenomena have been, since the publication 

 of their observations, the subject of many experiments, observa- 

 tions, and debates, and various theories have been brought forward 

 to explain the typical breathing ; a historical account and original 

 observations are given by Gibson ( 35 ) in his monograph upon the 

 subject. Recently Pembrey and Allen ( 36 ) have determined the 

 composition of the alveolar air at different stages of the waxing 

 and waning respiration of a patient who showed well-marked 

 Cheyne-Stokes's respiration. The following are some of the results 

 of the analyses : 



In the case of the early period of waxing respiration and of 

 the late period of waning respiration the true values of the carbon 

 dioxide are probably higher, and of oxygen probably lower, owing 

 to the shallow nature of the respirations. When the patient was 



