20 



AMOUNT OF i;LOOD EXISTING IN ANIMALS. 



Gavarret, and Delafond. The fibrin, however, was not determined. The follow- 

 ing are the results which they obtained with the blood of the Mammals : — 



Having examined in detail the blood of cold and warm-blooded animals in a 

 normal condition, we shall next compare the individual results and analyses 

 together, and endeavor to point out the characteristic distinctions of the blood of 

 these two great classes of animals. 



Amount of Blood existing in the Bodies of Warm- and Cold-blooded Animals 



in a Normal State. 



In determining the amount of blood, several methods have been employed by 

 different chemists and physiologists. 



M. Valentin 1 adopted the following ingenious mode : — 



Having weighed the animal, he abstracted a definite amount of blood, deter- 

 mined its solid constituents, and then injected a given quantity of distilled water 

 into the bloodvessels. Time was allowed for the diffusion of this by the circula- 

 tory apparatus throughout the mass of the blood. A fresh portion of blood was 

 then abstracted, and the amount of solid matters determined. The relation between 

 the amount of solid matters in the blood first drawn and the blood diluted with a 

 given quantity of distilled water, enabled him to calculate the quantity of the 

 entire blood of the animal. 



Although this method is sufficiently accurate for general purposes, still the fol- 

 lowing objections have been urged against it with justice. 



The water injected is not diffused uniformly throughout the mass of blood. 

 This is determined by the fact that the blood drawn from different veins yields 

 different proportions of water and solid matters. When an excess of water is in- 

 jected into the circulatory system, it has a tendency to lodge in certain organs, as 

 the kidneys and spleen, and in a less degree in the lungs. Other circumstances 

 affect the accuracy of the results; as the loss of blood in any of the steps of the 

 operation, the elimination of the water by evaporation from the surface of the lungs 

 and skin, and by the action of the kidneys, and exosmose into the surrounding 

 tissues in the interval of time between the injection of the water and the abstrac- 

 tion of the second portion of blood. 



Eept. der Physiol , Bd. s. 281-293. 



