ACCUMULATION OF HEAT IN THE BODY. 403 



which these diminish the body becomes less capable of withstanding 

 the surrounding heat, and thus is readily explained the fact that the 

 human being is by far less able to withstand air rich in watery vapor 

 than dry air at the same temperature, as heat must, under such circum- 

 stances, accumulate within the body. Thus in the Russian steam -bath 

 at a temperature of from 53 to 60 C. the normal rectal temperature 

 rises to between 40.7 and 41.6 C. A human being is just able to work 

 in an atmosphere at a temperature of 31 C. almost completely saturated 

 with watery vapor. 



In water at the temperature of the body the normal bodily temperature rises 

 i C. in one hour; about 2 C. in one and one-half hours . Gradual elevation of the 

 temperature of the water from 38.6 to 40.2 C. caused an increase in the axil- 

 lary temperature to 39 C. within fifteen minutes. 



ACCUMULATION OF HEAT IN THE BODY. 



As under normal conditions the constancy of the bodily temperature 

 is the result of a constant relation between heat-production and heat- 

 dissipation it is obvious that heat must be stored up in the body when 

 heat-dissipation is lessened. The chief organ regulating heat-dissipation 

 is the external integument. Contraction of the skin and its vessels 

 diminishes heat-dissipation, while relaxation with dilatation of the ves- 

 sels increases heat-dissipation. Accumulation of heat may, accordingly, 

 be effected : 



(a) By intense and extensive cutaneous irritation, through which a 

 transitory influence is exerted, causing contraction of the skin and its 

 vessels. (6) Also through other forms of restriction of loss of heat 

 through the skin, (c) Through increased activity of the vasomotor 

 center, as a result of which contraction of all vessels, and naturally 

 also those of the external integument, is brought about. In thi's 

 way the elevation of temperature following transfusion of blood from 

 an animal of the same species is to be explained direct transfusion 

 of arterial blood from the crural artery into the adjacent vein in the 

 same animal will suffice, as Landois was able to confirm by experiments 

 on the carotid and the external jugular vein as well as that following 

 venesection after a preceding decline in temperature. In both events 

 abnormal blood-distribution takes place. In the first the venous system 

 is abnormally overloaded, in the second abnormally empty. For the 

 restoration of the normal distribution vigorous activity on the part of 

 the musculature of the vessels is necessary, excited through the vaso- 

 motor center. The marked contraction of the cutaneous vessels hereby 

 brought about exerts an inhibitory influence on heat-dissipation and 

 heat-accumulation thus takes place. The elevation of temperature 

 observed after sudden abstraction of water from the body must appa- 

 rently be explained in the same way. The inspissated blood requires 

 less vascular space and the contracted vessels permit the escape of little 

 heat into the skin, (d) If the circulation through the cutaneous vessels 

 in considerable areas is retarded by mechanical means, as by occlusion 

 of small vessels by viscous masses of stroma or coagula, which form 

 after transfusion of blood from an animal of a different species, accumu- 

 lation of heat takes place likewise in consequence of diminished dissipa- 

 tion. Perhaps a number of other pyrogenic agents act in the same 

 manner. In dogs in which both carotids and both axillary and crural 



