874 SPECIAL PHYSIOLOGY. 



perature is lowered to about 43, then the animal is from 2 to 3^ warmer. 

 The edible frog, inclosed in ice at 21, has exhibited a temperature of 37^. 



In Reptiles, the temperature of the body is still higher, though yet it is 

 dependent on the external temperature. The turtles produce less heat than 

 the serpents, crocodiles, and lizards ; the temperature of some of the latter 

 has been found to be 86, that is, 15 higher than that of the surrounding air. 

 These facts show that in the cold-blooded animals, the temperature is greatly 

 dependent on, and regulated by, that of the surrounding medium, but also that 

 there is a moderate individual heat-producing power even in them. This 

 power, moreover, absolutely increases, like the functions of the animal gener- 

 ally, at still higher temperatures ; but yet so as not to enable the animal to 

 reach that temperature. 



In the Warm-blooded animals, the temperature is high and constant, and, 

 as already mentioned, is, within certain limits, plainly independent of the 

 external temperature, owing to special powers exercised within their bodies. 

 Amongst the Mammalia, the average temperature of the body is lower than 

 that of Birds, which present the highest temperature of any animals, although 

 their general organization places them in a lower rank than the Mammals. 

 The ordinary range in the Mammalia, is from 97 to 104; in Birds, it varies 

 from 100 to 108, or even 111. In the sheep, the temperature has been found 

 to be from 103 to 105 ; in the pig, 106 ; but in the Arctic fox, it has been found 

 to be 107, the air being only 14. In sea-birds, as in the gulls, the tempera- 

 ture is lower than in other birds, varying from 100 to 105 ; in the common 

 fowl it ranges from 107 to 110, according to the climate and season ; and in 

 the swallow, it is even 111. (J. Davy.) 



The temperature of the tissues of the human body, speaking gener- 

 ally, ranges between 98 and 100; but that of the blood, which is the 

 hottest part of the organism, ranges from 100 to 102. The blood 

 varies in temperature in different parts, being the hottest in the hepatic 

 veins, which bring the blood from the liver ; this blood is somewhat 

 warmer than that of the vena portce, and even 1 higher than the blood 

 of the aorta. (Bernard.) Directly opposite statements have been made 

 as to the temperature of the blood, before and after it has passed 

 through the lungs ; but the most recent researches favor the conclusion 

 that the blood in the left side of the heart is nearly i lower than in the 

 right side of that organ ; a slight cooling process is supposed to occur in 

 the lungs from the air admitted into them. The blood of the superficial 

 veins of the limbs, coming from the exposed skin, is naturally cooler, 

 from the influence of the atmosphere, than that of the arteries, which 

 lie deeper ; the temperature of the blood in the deep veins, as in the 

 femoral vein, is also said to be about 1 cooler than that in the femoral 

 artery. (Becquerel and Breschet.) The relative warmth of the organs 

 and tissues, always less than that of the blood, depends on their vas- 

 cularity, their distance from the central part of the body, or their 

 proximity to the surface, and on the degree to which they are pro- 

 tected by external covering. Thus, whilst the temperature in the ab- 

 domen (in the bladder), has been found to be nearly 102, even higher 

 than that of the thorax, the temperature under the tongue is about 98; 

 and in the axilla 96 ; that of the hands and feet may ordinarily be from 

 9 to 12 cooler than the central parts, i. e., from 90 to 93. 



Various conditions modify the temperature of the human body; 

 neither age nor sex produce any remarkable difference. The temper- 

 ature of infants and of old persons is about normal, so long as they 



