V TEMPERATURE OF THE BODY 203 



body, and of the whole body, at different times, are very 

 different ; and as some parts of the body are so situated 

 as to lose their heat by radiation and conduction much 

 more easily than others, the temperature of the body 

 would be very unequal in its different parts, and at 

 different times, were it not for the arrangement by which 

 the heat is distributed and regulated. 



Whatever oxidation occurs in any part, raises the tem- 

 perature of the blood which is in that part at the time, 

 to a proportional extent. But this blood is swiftly hurried 

 away into other regions of the body, and rapidly gives up 

 its excess heat to them. On the other hand, the blood 

 which, by being carried to the vessels in the skin on the 

 surface of the body begins to have its temperature lowered 

 by evaporation, radiation, and conduction, is hurried 

 away, before it has time to get thoroughly cooled, into the 

 deeper organs ; and in them it becomes warm by contact, 

 as well as by the oxidating processes there going on. 

 Thus the blood-vessels and their contents may be 

 compared to a system of hot-water pipes, through which 

 the warm water is kept constantly circulating by a pump ; 

 while it is heated not by a great central boiler as usual, 

 but by a multitude of minute gas jets, disposed beneath 

 the pipes not evenly, but more here and fewer there. It 

 is obvious that, however much greater might be the heat 

 applied to one part of the system of pipes than to another, 

 the general temperature of the water would be even 

 throughout, if it were kept moving with sufficient quick- 

 ness by the pump. In this way, then, the temperature of 

 the body is kept uniform in its several parts. 



12. Regulation of Body-temperature by Altered 

 Loss of Heat. — If a system such as we have just 

 imagined were entirely composed of closed pipes, the 

 temperature of the water might be raised to any extent 

 by the gas jets. On the other hand, it might be kept 

 down to any required degree by causing a larger, or 

 smaller, portion of the pipes to be wetted with water, 



