546 EVOLUTION OF HEAT, LIGHT, AND ELECTRICITY. 



be no doubt, is sufficiently explained by the relaxation of the walls of the 

 smaller arteries (producing a state resembling a permanent "blush"), and 

 the consequent increase in the flow of blood through the part, which has 

 been shown by Dr. Aug. Waller to result from this operation. (See 254.) 

 A curious experiment made by Bernard tends to show that the quantity of 

 blood taken up by any one organ is supplied to it at the expense of another; 

 and that the excess of heat developed at one point of the body is compen- 

 sated for by a diminution in some other part. He found that on making a 

 section of the Sympathetic in the neck of a Rabbit, both of whose ears had 

 previously a temperature of 95 F., the temperature rose to 100 F. on the 

 side on which the section was made, whilst it fell to 91 F. on the opposite 

 side. When, however, the peripheral end of the cut nerve was galvanized, 

 the temperature fell in the corresponding ear, and rose in the opposite one. 1 

 Local variations of temperature occur in the various organs in consonance 

 with the changes in the circulation in them resulting from the active perform- 

 ance of their duties, or their state of repose. In some instances, however, 

 such variations seem to be independent of changes in the supply of blood. 2 

 Thus Sch iff 3 has shown that irritation of a sensory nerve in a dog under the 

 influence of woorara, and therefore incapable of performing muscular move- 

 ments, causes increase of the temperature of one or the other hemisphere of 

 the brain, and was independent of changes in the circulation, since it oc- 

 curred even as late as twelve minutes after the heart's action had ceased. 

 Even irritation of the nerves of special sense will produce this effect, for it 

 was distinctly perceptible in a thoroughly woorarized dog before which an 

 umbrella was suddenly opened. In accordance with this, though perhaps 

 other circumstances lead to the increase of temperature, is the observation 

 made by Bernard, 4 that if the foot of a dormouse be pinched whilst in a 

 state of hibernation, the temperature rises almost immediately as much as 

 from 60 to 70 F. In opposition to it is the statement made by Horvath, 5 

 that irritation of a sensory nerve causes depression of the temperature in the 

 rectum. 6 Horvath having observed that mere binding of a rabbit so that it 

 could not move, caused a gradual fall of temperature, sometimes to as much 

 as 3 Fahr., at first attributed it to its cramped condition; but further ex- 

 periments led him to conclude that it was due to the pain experienced by 

 the animal when its limbs were tightly bound. Fuuke 7 states that intel- 

 lectual exertion causes an increase of temperature in the brain. A consid- 

 erable fall of temperature occurs during the narcotic condition induced by 

 chloroform, 8 which is probably partly due to its depressing influence upon 

 the circulation, as well as to its direct action upon the blood-corpuscles. In 

 like manner in poisoning by woorara, which C. Bernard has shown first par- 

 alyzes the vaso-motor nerves, causing dilatation of the cutaneous capillaries, 

 and consequent increased loss of heat, and at the same time, a retardation of 

 the movements of the heart and respiratory muscles, a decline of temperature 

 is constantly observed. Jacobson and Landre 9 have shown that there is sim- 

 ilarly a decline in the temperature of the rectum. [Bernard considers that 

 the muscular and nervous systems are important sources of heat. In the ex- 

 tremities and on the surface of the body the venous blood is always cooler 



1 Bernard, Logons, 1859, Geme 



2 Many instances of'local variations in disease have been collected by Wunderlich. 



3 Archives do Physiolotrie, 1870, p. 198. 4 Rev. Scient., 1871, p. liS.S. 

 5 Centralhlatt, 1870, p. 646. 6 Sec also Heidenhain, Oentralblatt, 1809. 



7 Physiologic, 1873, p. 306. 



8 See Schi'incsson, Dissert, iiber d. Einfluss d. Chloroform : quoted by Funke, Phys- 



1872, p. 308. 



9 JNederland. Archiv v. Genees en Naturk., Bd. ii, p. 355. 



