SEC. 4. THE QUANTITY OF BLOOD, AND ITS 

 DISTRIBUTION IN THE BODY. 



The total quantity of blood present in an animal body is 

 estimated in the following way. As much blood as possible is 

 allowed to escape from the vessels; this is measured directly. 

 The vessels are then washed out with water or normal saline 

 solution, and the washings carefully collected, mixed and measured. 

 A known quantity of blood is diluted with water or normal saline 

 solution until it possesses the same tint as a measured specimen of 

 the washings. This gives the amount of blood (or rather of 

 haemoglobin) in the measured specimen, from which the total 

 quantity in the whole washings is calculated. Lastly, the whole 

 body is carefully minced and washed free from blood. The 

 washings are collected and filtered, and the amount of blood in 

 them estimated as before by comparison with a specimen of diluted 

 blood. The quantity of blood in the two washings, together with 

 the escaped blood, gives the total quantity of blood in the body. 



The method is not free from objections, the most serious 

 of which perhaps are attached to the difficulty of obtaining 

 infusions of the minced tissues clear enough to have their tint 

 accurately estimated, and to the fact that the animal must be 

 killed for the purpose; but other methods, for instance those in which 

 the quantity is calculated from the proportion of red corpuscles to 

 plasma before and after either diminution of the plasma by sweat- 

 ing or increase by the injection of serum or other fluids free from 

 corpuscles, are open to still graver objections. 



F. 3 



