VASOMOTOR CONTROL OF TEMPERATURE. 855 
vessels, the difference between the temperature of the skin and its 
surroundings is increased, and likewise the loss of heat. Thus the first 
effect of a warm bath may be a fall in the temperature of the internal 
parts. The loss of heat by this flushing of the skin with hot blood and 
by sweating may be very great, as shown by the rapid fall in tempera- 
ture during the sweating state of ague or the crisis of pneumonia. 
These changes in the calibre of the vessels can be brought about 
reflexly, not only by sensations of heat and cold but by those of pain : 
further, emotions can effect these changes, as in the blushing of excite- 
ment or shame, and the pallor of fright or anger : in fact, emotions may 
in different individuals have opposite effects upon the vascularity of the 
skin. 
An impression conveyed by the sensory nerves of one part of the 
body can influence the calibre of the vessels, not only on the same side 
but also on the opposite side. Thus, Brown-Seipiard and Tholozan, 1 found 
that plunging one hand in warm water raised the temperature of the 
opposite hand also. Waller,- however, has failed to confirm this. 
The explanation of the part played by the vasomotor nerves in 
the regulation of temperature is not so simple as may appear from a 
first consideration, for the problem is complicated by the fact that 
an increase or decrease in the vascularity of the skin is accom- 
panied by a similar change in the production of sweat ; further, it is 
possible that the alterations in vascularity may affect the metabolism 
of the tissues. Upon this latter point there has been considerable dis- 
cussion. The first and most important experiment in this connection 
is that of Bernard, 3 who found that section of the cervical sympathetic 
caused a dilatation of the blood vessels and a rise of temperature in the 
ear of the same side. The enlargement of the blood vessels results in a 
greater and more rapid flow of blood through the ear, and this would 
naturally raise the temperature of the part. Bernard, however, did not 
look upon this explanation as complete ; he held that the nervous 
system regulated not only the circulation but also the production of 
heat in the tissues, for he states, among other arguments, that section of 
the cervical sympathetic, after previous ligature of the veins of the ear, 
still caused a rise of temperature. According to Bernard, the nerve was 
both vaso-constrictor and frigorific. It was to be expected, how r ever, 
that this view would be contested, for although a certain amount of 
heat would be produced in the ear, as in the metabolism of all tissues, 
yet that amount would be small, for the cartilage and other tissues of 
the ear are not the seats of an active exchange of material. 
Numerous experimenters i have decided against Bernard's theory, and 
have attributed the changes in the temperature of the ear to alterations 
1 Journ. de Vanat. et physio!, etc., Paris, 1858, tome i. p. 497. 
2 Note communicated to the writer. 
D " Lecons sur la physiologie et la pathologie du systeme nerveux," 1858, tome ii. 
p. 490 ; "Lecons sur la chaleur animale," 1876, p. 297. 
4 Brown-S6quard, Med. Exam., Philadelphia, 1852, p. 489, and 1853, p. 9 ; Budge, 
Compt. rend. Acad. d. sc., Paris, tome xxvi. p. 337; Ztschr. r. d. Verein f. Heilk. in 
Preussen, 1853, Bd. xxii. S. 149 ; Waller, Compt. rend. Acad. d. sc, Paris, 1854, 
tome xxxvi. p. 378: De Ruyter, "De actione atropse belladonnas," Diss., 1853; Schiff, 
"Untersuch. z. Physiol, des Nervensystems," 1855, Bd. i. S. 124 ; AUg. JVien. med. Ztg., 
1859, S. 318 ; Kussmaul and Tenner, Untersuch. z. Naturl. d. Mcnsch. u. d. Thiere, 
1855, Bd. i. S. 92 ; Callenfels, Ztschr. f. rat. Med., 1858, Bd. vii. S. 157 ; Jacobson and 
Landre, Nederl. Tijdschr. v. Geneesk.,_ Amsterdam, Bd. i. Heft 3 ; Donders, "Witnderlicb's 
"Medical Thermometry," p. 148; Baylissand Hill, Journ. Physiol, Cambridge and London, 
1894, vol. xvi. p. 351. 
