TEMPER. I Tl RE OF THE SKIN. 829 
It will be seen from the two tables that the results lead to directly 
opposed conclusions, but a critical examination shows that the correct 
one is probably that the blood in the right ventricle is o- l to o- 2 
wanner than that in the left. In many of the older experiments the 
methods were inexact, the chest was opened and the heart exposed; 
the right ventricle, on account of its thin walls, would cool more quickly 
than the left, as shown experimentally by G. Liebig. The most exact 
method appears to be the insertion of delicate thermometers or thermo- 
electric needles down the jugular vein and the carotid artery into the 
right and left ventricle respectively. This method was employed by 
Heidenhain and Korner l in numerous experiments upon dogs, with the 
result that in all but one of the observations the right side of the heart 
was warmer than the left. Thus in one case the difference was '6°, 
in two - 5° to "6°, in three '5°, in five "3° to - 4 . in twenty-seven "2° to '3°, 
in thirty-six "l to '2°, in twenty-one "15°, in one case no difference at 
all. To determine whether the inspiration of cold air was the cause of 
this difference, Heidenhain and Korner made comparative experiments, 
employing for artificial respiration in the one case cold air (17°), and in 
the other hot air (40 ") saturated with moisture. The difference still 
remained, and it was therefore concluded that respiration was not the 
cause ; cold air when inspired is warmed and saturated with moisture 
before it reaches the alveoli ; 2 further, in passing through the upper 
parts of the respiratory tract, the cold air would cool the blood in veins 
going to the superior vena cava and thus to the right side of the heart. 
These observers conclude that in the dog the right ventricle is warmer 
than the left, because its walls lie nearer to the liver and other 
abdominal organs, which have a high temperature, while the left 
ventricle is surrounded by lung. It was found, in fact, that the 
difference in temperature could be reduced to a minus quantity by 
artificially lowering the temperature of the abdominal cavity. Bernard 
does not accept this explanation as satisfactory ; for he points out that 
in Hering's observation the right ventricle was half a degree warmer 
than the left, although the heart, owing to a congenital defect, was 
outside the thorax. 
The temperature of the skin. — The temperature of the human skin 
shows differences in different parts of the body, and is also subject to 
variations due to alterations in the external temperature, the amount of 
natural or artificial covering, the vascularity of the parts, and the 
amount of evaporation taking place from the surface. Apart from 
these variations, there is a difficulty in measuring accurately the 
temperature of the skin ; a mercurial thermometer applied to the skin 
receives heat from the surface in contact with the skin, and loses 
heat from the surface exposed to the air. If, on the other hand, 
the thermometer is covered with a non-conductor, or the external 
temperature is raised, then the heat of the part of the skin observed 
is increased. To overcome these difficulties, thermo-electric methods 
have been used. 3 
The disadvantages of these thermo-electric methods are the complexity 
1 Arch. f. d. ges. Physiol., Bonn, 1871, Bd. iv. S. 558. 
2 See "Chemistry of Respiration, " this Text-book, vol. i. p. 754. 
3 Christiani and Kronecker, Arch. f. Physiol., Leipzig, 1878, S. 334; Kunkel, Ztachr.f. 
Biol., Munchen. 1889, Bd. xxv. S. 55 ; Masje, Virchow's Archiv, Bd. cvii. S. 17, 267 ; 
Geigel, Verhandl. d. phys.-med. Gesellsch. in IViirzburg, 1888, N. F., Bd. xxii. S. 8 ; 
Stewart, Stud. Physiol. Lab. Owens Coll., Manchester, 1891, vol. i. p. 100. 
