ADVANCED DEMONSTRATIONS 



411 



(3) One thermometer is inserted at the junction of the subclavian 

 and jugular veins, and pushed down into the vena cava inferior. This 

 thermometer will register a temperature slightly higher than that in 

 the aorta. On the contrary, the blood in the superficial veins, for 

 example, in the femoral vein, is cooler than the arterial blood. 



35 



FIG. 265A. Thermo- 

 meter for determining 

 temperature of blood. 



FIG. 265B. Thermo- 

 electric needle. 



FIG. 265c. Thermo- 

 electric catheter. 



Mosso asserts that the brain is an active seat of heat-production. It 

 is questionable whether he measured the true aortic temperature. His 

 results can be attributed to the varying amount of blood which 

 circulated through the brain during the experiments. The estimations 

 of the exchange of blood gases in the brain made by Hill and Nabarro 

 do not favour Mosso's conclusions. The muscles are the only organs 

 in which the production of heat has been certainly demonstrated by 

 thermometric methods. Thermo-electric junctions are made by solder- 

 ing the ends of an iron and a German-silver wire together. An alloy 



