EVOLUTION OP HEAT. 537 



ami the large amount of caloric which is consumed in this change, is for the 

 most part withdrawn from the body, the temperature of which is thus kept 

 down. By some experimenters, as by Ackermann, 1 an attempt has been 

 made to show, that the lungs as well as the skin, constitute a regulating 

 mechanism for preserving an equality of the temperature in warm-blooded 

 animals ; since if an animal be exposed to a gradually increasing tempera- 

 ture its temperature rises, but its respirations also increase in number, quite 

 apart from the deficiency of oxygen or increase of carbonic acid in the blood, 

 and ultimately a form of dyspnoea is produced, due simply to heat. 2 The 

 increased number of respirations ou exposure to warm air does not, according 

 to Riegel, 3 occur in rabbits and dogs in which the spinal cord has been divided 

 high up, and the temperature of the animal continues to rise. In Riegel's 

 experiments on animals under the influence of woorara, and in which artificial 

 respiration was maintained, all conditions of the experiment remaining the 

 same, the temperature invariably fell in proportion as respiration was quick- 

 ened. It is difficult to say whether the power of generating heat which the 

 body possesses is capable of being self-regulated or governed in conformity 

 with the external conditions that may at any time be present; that is to say, 

 whether when the body is exposed to cold more heat is produced, and when 

 to heat, less. Liebermeister 4 found that in a cold bath, or on exposure of 

 the surface to cool air (54-70 c F.), the temperature of the interior of the 

 body in the first instance rose slightly or remained stationary, though it fell 

 after long immersion or exposure. It fell also after removal from the cool- 

 ing influence. This he explained by considering that the body possesses the 

 power of generating more heat when required, though this power is limited ; 

 whilst the secondary fall, when there is no longer any withdrawal of heat, is 

 due to the cooling of the blood circulating in the capillaries of the cool skin. 

 Keriug' 1 endeavored to furnish a further proof by showing that with increase 

 of external heat, or by preventing the body from losing its temperature, a 

 diminished production of heat takes place. Jurgeuseu 6 and Senator 7 op- 

 pose these statements, and maintain that when the body is exposed to cold, 

 there is no increased production of heat, but the superficial vessels contract, 

 and a badly conducting superficial layer of tissue exists, so that the blood 

 in the deeper organs is prevented from giving off its heat, and thus with 

 unaltered production of heat may rise in temperature. As soon as the ex- 

 posure to cold ceases, the cutaneous vessels dilate, and the blood circulating 

 through the cooled part leads to a fall of temperature. Fuuke 8 considers 

 that the rapid rise that occurs in the temperature of the body in animals 

 that have been thoroughly cooled, when placed under favorable circum- 

 stances, is in favor of Liebermeister and Kering's views. Exposure to in- 

 tense cold causes a fall of the temperature of the whole body from the first, 

 and vice versa during exposure to a hot bath. The temperature may rise 

 above that of the bath. 9 



1 Archiv f. Klin. Med , Bel. ii, p. 361. See Woodman's Abst. of Kiegel's paper in 

 Lond. Med. Record, 1874, p. 744. 



2 See also Fick and Goldstein, Ueber Warmdyspncea, Inaug. Abhand , Wurzburf, 

 Verhand., 1871. 



3 Virchow's Archiv, Bd. Ixi, Heft 3. 



4 Archiv fur Anatomic u. Physiol., I860, pp. 520 and 589; 1861, p. 28; 1862, p. 

 661 ; Archiv f. Klin. Medicin, Bd. v, p. 217. 



5 Experiment. Beitra'o;. zur Kenntniss d. Wiirmeregulirung Diss., Dorpat, 1864. 



6 Deutsch. Archiv f. Klin. Med., Bd. iv, p. 323. 



' 7 Virchow's Archiv, Bd. xlv, p. 351 ; Bd. 1, p. 354 s Physiologie, 1873, p. 308. 



9 Schuster, Deutsche Klinik, 1864, pp. 216, 229, 248; Rohrig and Zuntz, Pfliiger's 

 Archiv, Bd. iv, p. 57 ; Murri, Del potere regulatore della tempemtura animale ; 

 Pamphlet, Firenze, 1873 ; liosenthal, Centralbhitt, 1872, p. 840. 



35 



