THE BLOOD FLOW 



397 



Carotid artery. . . 

 Femoral artery . . , 

 Hepatic artery . . . 

 Thyroid artery . . . 

 Ext. jugular vein. 



Renal vein 



Mesenteric vein . . 



Splenic vein 



Portal vein 



Femoral vein 



The indirect method of measuring the blood flow embraces several different 

 procedures, namely, the calorimetric, plethysmographic, and the gas-analytical. 

 The calorimetric method devised by Stewart^ arrives at the quantity of blood 

 traversing a part, by measuring the amount of heat liberated by it in a certain 



Fig. 209. — Calorimetric Method of Measuring Blood-flow in Hands. (From 

 Stewart's "A Manual of Physiology ," William Wood and Co., Publishers.) 



period of time and by ascertaining the difference in the temperatures between 

 the inflowing and outflowing blood. This method is applicable to the human being. 

 Having established the basal temperature by immersing the hands or feet for some 

 time in water, the temperature of which is one or two degrees below that of the 

 arterial blood, they are rapidly transferred to a calorimeter filled with water of the 

 same temperature. As the parts are kept motionless, the heat given off by them 

 while in this compartment, must be derived chiefly from the blood passing through 

 them. The temperature of the arterial blood at the wrist was found to be lower 

 by 0.5° C. than that of the rectum, while the venous blood exhibited a temperature 



* Cleveland Med. Jour., x, 1911, and Heart, iii, 1911. 



