REGULATION OP THE TEMPERATURE. 443 



the periphery, and the transverse thermal conduction through the skin, 

 are diminished by the contraction of the vessels and muscles of the 

 skin, and by the expulsion of the well conducting blood from the 

 cutaneous and sub-cutaneous vessels. The cooling of the body is very 

 much affected, owing to the diminution of the cutaneous blood-stream, 

 just as occurs when the current through a coil or worm of a distillation 

 apparatus is greatly diminished (Winternitz). If the blood-vessels 

 dilate, the temperature of the surface of the body rises, the difference 

 of temperature between it and the surrounding cooler medium is 

 increased, and thus the excretion of heat is increased. Tomsa has 

 shown that the fibres of the skin are so arranged anatomically, that 

 the tension of the fibres produced by the erector pili muscles causes a 

 diminution in the thickness of the skin, this result being brought about 

 at the expense of the easily expelled blood. 



Landois and Hauschild ligatured the arteries alone, or the arteries 

 and veins (dog) e.g., the axillary artery and vein, the crurals, the 

 carotids and the jugular veins, and found that in a short time the 

 temperature rose several tenths of a degree. 



By the systematic application of stimuli e.g., cold baths, and washing with 

 cold water, the muscles of the skin and its blood-vessels may be caused to con- 

 tract, and become so vigorous and excitable, that when cold is suddenly applied 

 to the body or to a part of it the excretion of heat is energetically prevented, so 

 that cold baths and washing with cold water are, to a certain extent, "gym- 

 nastics of the cutaneous muscles," which, under the above circumstances, protect 

 the body from cold (Rosenthal, du Bois-Reymond). 



(2.) Increased temperature causes increased heart-beats, while 

 diminished temperature diminishes the number of contractions of the 

 heart (p. 105). The relatively warm blood is pumped by the action of 

 the heart from the internal organs of the body to the surface of the skin, 

 where it readily gives off heat. The more frequently the same volume 

 of blood passes through the skin 27 heart-beats being necessary for 

 the complete circuit of the blood the greater will be the amount of 

 heat given off and conversely. Hence, the frequency of the heart-beat 

 is in direct relation to the rapidity of cooling (Walther). In very hot 

 air (over 100C.) the pulse rose to over 160 per minute. The same is 

 true in fever (p. 142). Liebermeister gives the following numbers 

 with reference to the temperature in an adult: 



Pulse-beats, per min., 78'6 91 '2 99'8 108'5 110 137 '5. 

 Temperature in C., 37 38 39 40 41 42. 



(3.) Increased temperature increases the number of respirations. 

 Under ordinary circumstances, a much larger volume of air passes 

 through the lungs when it is warmed almost to the temperature of the 



