34 DISTRIBUTION OF BLOOD. [BOOK i. 



From the result of a few observations on executed criminals it 

 has been concluded that the total quantity of blood in the human 

 body is about -^th of the body weight. But in various animals, 

 the proportion of the weight of the blood to that of the body has 

 been found to vary very considerably ; and probably this holds good 

 for man also, at all events within certain limits. 



The blood is in round numbers distributed as follows : 



About one-fourth in the heart, lungs, large arteries and veins, 



liver, 



skeletal muscles, 



other organs. 



Since in the heart and great blood-vessels the blood is simply 

 in transit, without undergoing any great changes (and in the lungs, 

 as far as we know, the changes are limited to respiratory changes), 

 it follows that the changes which take place in the blood passing 

 through the liver and skeletal muscles far exceed those which take 

 place in the rest of the body. 



