310 PHYSIOLOGY. 



placed in a hot oven, it soon dies, because the exhalation 

 from the body is prevented. It is for this reason, also, that 

 we feel the heat more in damp weather than in dry, although 

 the temperature be lower. Such weather is called sultry, 

 close, muggy, <$>c., because the saturation of the air by 

 moisture, prevents the escape of heat by evaporation from 

 our bodies. 



21. In infancy, the faculty of generating animal heat is 

 much less than in adult age. This is the chief cause why 

 so many perish during the first years of life, and particular- 

 ly in winter, during the first few days. At this ^period, the 

 temperature of infants is only about ninety-three degrees, 

 and in some instances not more than eighty, and is rapidly 

 diminished by slight exposures. This shows the great im- 

 portance of guarding against the effect of cold, by proper 

 clothing, and a regulated temperature of houses. Man 

 has no natural protection against the influence of cold, but 

 reason was given him as a substitute. How few appear 

 to employ this faculty, in guarding against atmospheric 

 vicissitudes by a proper adaptation of the dress ; and in 

 consequence, how many, instead of consulting their health, 

 comfort, and usefulness, fall victims to negligence or fashion ! 



Questions. What is calorification ? What are the causes of animal 

 heat ? Why was it surmised that respiration was concerned in this 

 process ? What objections to this ? What was Crawford's hypothesis ? 

 What occurs when respiration is impeded? What occurs in cold- 

 blooded animals ? How much heat, according to Magendie, is produced 

 by respiration in herbiverous animals ? in carniverous ? in birds 7^^- 

 Is arterial blood warmer than venous > -.How much heat does the blood 

 acquire in passing through the lungs ? Hqw many degrees does the 

 system acquire from this source in 24 hours ^ ' What is Brodie's theory 

 with respect to animal heat ? What facts in favour of it ? What is 

 said of animal heat being generated in the capillary system ? What 

 axiom in relation to a change in the particles of bodies has a bearing 

 on this subject ? What conditions are necessary to the production of 

 animal heat by the action of the capillaries ? How is this proved ? 



