Gases of the Blood 939 



the usual conditions of respiration, is the arterial blood saturated 

 with oxygen, nor does it contain all the oxygen that it can absorb 

 by agitation with air. Nothing is more variable than this differ- 

 ence between the amount of oxygen which the arterial blood does 

 contain and that which it can contain. 



There are therefore individuals in whom a certain increase in 

 the rapidity and amplitude of the respiratory movements can in- 

 crease considerably the oxygen of the blood, and others, on the 

 contrary, who can get almost no advantage from it. These two 

 classes will, therefore, not be in identical conditions, from the point 

 of view, for example, of diminution of pressure. Inversely, there 

 are individuals who, being more saturated already, will be far 

 more able than others to bear a certain slowing down of respira- 

 tion, without having the proportion of the oxygen of their blood 

 fall to too low a figure. 



In a general way, the oxygen content of the blood is shown by 

 the red coloration, and the redder a blood is, the more oxygen it 

 contains. But that is absolutely true only of the same blood. My 

 analyses have very often shown me, on the contrary, that certain 

 light red bloods were poor in oxygen, compared to other bloods 

 with a dark shade. 



That is because the redness shows only the oxygen content of 

 the hemoglobin (oxy-hemoglobic combination). If we imagine two 

 bloods containing the same quantity of oxygen, the one which is 

 very rich in hemoglobin will be considerably less red than the other. 

 I have indeed after a copious bleeding found a blood redder than 

 or as red as before, although with a considerably lower oxygen 

 content; only the tint was lighter, because the blood was less laden 

 with corpuscles. 



This occurs in young animals. Experiments CCCII and DCXLV 

 showed us in puppies a light red blood which contained only 9.4 

 and even 7.3 volumes of oxygen. This explains the low resistance 

 of young animals (I am not speaking of new-born animals, of 

 course) to asphyxia, chilling, etc. They are, in the highest degree, 

 anoxyhemic. 



My analyses show also that in sick animals the quantity of 

 oxygen contained in the arterial blood is very small. Indeed, it 

 dropped, for example, to 13.3 in the dog of Experiment CLXXIV, an 

 animal which was suffering from a festering wound resulting from 

 bleedings, and which, when healthy, had given 19.4 (Exp. CLXXI) . 

 It seems to me extremely probable that in certain cases of sick- 

 ness, the lessened quantity of oxygen contained in the blood must 



