ANIMAL HEAT 517 



quently diminished loss and increased production may 

 be both involved ; and it ought to be remembered that 

 the healthy standard with which the heat-production of a 

 fever patient should be compared is not that of a man 

 doing hard work on a full diet, but that of a healthy person 

 in bed, and on the meagre fare of the sick-room. When 

 this is kept in view, the comparatively low heat-production 

 and respiratory exchange which have sometimes been found 

 in fever cease to excite surprise. But, in any case, no mere 

 change in the relative proportions of heat formed and lost 

 is sufficient to explain the febrile rise of temperature. 

 That an increase in heat-production is not of itself enough 

 to produce fever is proved by the fact that severe muscular 

 work, which increases the metabolism more than high fever, 

 only causes in a healthy man a rise of about i C. in the 

 rectal temperature. When the work is over, the temperature 

 comes rapidly back to normal. The essence of the change 

 in fever is a derangement of the mechanism by which in the 

 healthy body excess or defect of average metabolism, or of 

 average heat-loss, is at once compensated and the equilibrium 

 of temperature maintained. 



This derangement only lasts as long as the temperature is 

 rising. When it becomes stationary at its maximum we 

 have again adjustment, again equality of production and 

 escape of heat ; but the adjustment is now pitched for a 

 higher scale of temperature. A rough analogy, so far as 

 one part of the process is concerned, may be found in the 

 behaviour of the ordinary gas-regulator of a water-bath. It 

 can be ' set ' for any temperature. That temperature, once 

 reached, remains constant within narrow limits of oscilla- 

 tion ; but the regulator can be equally well adjusted for a 

 higher or a lower temperature. 



Rosenthal has concluded from calorimetric observations 

 that, in the first stage of fever, while the temperature is 

 rising, there is always increased retention of heat. Marag- 

 liano actually found evidence, by means of the plethysmo- 

 graph, that the cutaneous vessels are at this stage con- 

 stricted, and that the constriction may even precede the 

 rise of temperature. Both observations lend support to the 



