TEMPERATURE TOPOGRAPHY 709 



and the hospital. For although hens are immune to anthrax under 

 ordinary conditions, but can be infected by inoculation when 

 artificially cooled, frogs, equally immune at the temperature of the 

 air, become susceptible when artificially heated. And it is impos- 

 sible to deny that the use of cold baths in typhoid fever is sometimes 

 of remarkable benefit. This benefit, however, while very unlikely 

 to be connected with any directly unfavourable action of the reduced 

 body-temperature on the growth of the bacilli, may perhaps be due, 

 in some part at least, to an increase in the cutaneous vaso-con- 

 striction which helps to send through the infected intestine a more 

 copious stream of blood. 



SECTION IV. DISTRIBUTION OF HEAT -TEMPERATURE 

 TOPOGRAPHY. 



The great foci of heat-formation the muscles and glands would, 

 if heat were not constantly leaving them, in a short time become 

 much warmer than the rest of the body ; while structures like the 

 bones, skin, and adipose tissue, in which chemical change and heat- 

 production are slow, would soon cool down to a temperature not 

 much exceeding that of the air. The circulation of the blood 

 insures that heat produced in any organ shall be carried away and 

 speedily distributed over the whole body; while direct conduction 

 also plays a considerable part in maintaining an approximately 

 uniform temperature. The uniformity, however, is only approxi- 

 mate. The temperature of the liver is several degrees higher than 

 that of the skin, and the temperature of the brain several degrees 

 higher than that of the cornea. The blood of the superficial veins 

 is colder than that of the corresponding arteries. 



The crural vein, for example, carries colder blood than the crural 

 artery, and the external jugular than the carotid. The heat produced 

 in the deeper parts of the regions which they drain is more than counter- 

 balanced by the heat lost in the more superficial parts. When loss of 

 heat from the surface is sufficiently diminished by an artificial covering, 

 or prevented by the protected situation of any organ with an active 

 metabolism, the venous blood leaving it is warmer than the arterial 

 blood coming to it. The temperature of the blood passing from the 

 levator labii superioris muscle of the horse during mastication may be 

 sensibly higher than that of the blood which feeds it ; the blood in the 

 vena profunda femoris, and in the crural vein of a dog with the leg 

 wrapped in cotton-wool, is warmer byo-ito 0-3 than of the crural 

 artery. The difference is due to the heat produced in the muscles, and it 

 ought to be of this order of magnitude. The quantity of blood in a 

 y-kilo dog is about kilo ; J of this, or ^ kilo, is in the skeletal muscles, 

 and the average circulation-time through them may be taken as ten 

 seconds. Six times in the minute, or 360 times in the hour, ^ kilo of 

 blood passes through the muscles, and is heated on the average by 0-2. 



"^60 "2 



This represents a heat-production of about ^- x , or 9 calories per 

 hour. Now, the total heat-production of a y-kilo dog is about 



