344 PULMONARY MUCOUS TISSUE. 



secretion of the sudoriferous glands ; we need only mention 

 in this place that the function of the exhalation from the skin, 

 alone explains why dry heat is more easily supported than 

 moist: evaporation is almost powerless against the latter, the 

 ambient medium being already almost saturated with vapor ; 

 on the other hand, surprising instances have been known of 

 extreme external heat being neutralized by violent sudation, 

 and considerable evaporation of sweat : thus, instances have 

 been known of persons who have supported for ten minutes 

 and more a temperature of 130 degrees (C.). In such cases 

 the secretion of the sweat becomes a hundredfold greater 

 than in the normal state, and, consequently, causes a great 

 loss of heat : the latent heat of the vaporization of water is 

 equal, as we know, to 540. 



Man's temperature, at every stage of his life, is connected 

 with the combustion which takes place in the tissues. The 

 temperature of an infant, just born, is nearly the same as our 

 normal temperature; it is only a little lower; a child of this 

 age is, however, very susceptible to outward changes in the 

 atmosphere, and is rarely capable of maintaining the tempera- 

 ture natural to it. Some general laws have been deduced from 

 experiments made on this subject. The temperature of those 

 animals, mammals or birds, which are born with the eyes 

 open, or with down upon their bodies, remains always the 

 same as at birth, provided there are no very decided causes 

 of loss (this being the case particularly in regard to man) ; 

 on the other hand, birds hatched without leathers, mam- 

 mals born with the eyes open, and children born prema- 

 turely, are unable to maintain this temperature. Thus a 

 rabbit cannot maintain that temperature, 35 or 36 deg. (C.), 

 which it had at birth: the want of activity of combustion is 

 the cause of all young animals offering so little resistance to 

 cold, while it is also the cause of their being able to resist 

 suffocation ; their respiration being less active than that of 

 adults, the want of oxygen has less effect upon them than 

 upon persons who require a large quantity for consumption 

 (adults, see p. 334). 1 



As respiration grows more active in man, so the heat pro- 

 duced increases, and the child, a few months after birth, is 

 enabled to support cold in a remarkable manner. Later, the 

 respiration of a young person is superior to that of the adult; 



1 'See Gavarret, " De la Chaleur produite par les Etres Vivants. " 

 Paris, 1855. 



