60 



PHYSIOLOGY 



CHAP. 



balance of the organism as a whole ; here we must confine our- 

 selves to the study of muscle as a thermogenic organ by the direct 

 examination of its temperature both during contraction and in the 

 resting state. 



The first observations were made in 1835 by Becquerel and 

 Brechet. They attached one couple of a thermo-electric battery 

 to the biceps muscle of a human arm, while the second couple 

 was kept at constant temperature. After a few contractions the 

 temperature of the muscle was raised 05, and after five minutes 

 of energetic alternate contraction and relaxation (working a saw) 

 1 C. Gierse (1842) was the first who noted in the dog, with the 



v_ 



Fio. 38. D'Arsonval's thermo-electric couples with sheathed junctions, to avoid the electrical 

 currents liable to be set up by the contact of two different metals with fluid. 1, Section of 

 finely-pointed conical tube of German silver, into which an iron wire has been soldered ; 2, 

 section of cylindrical tube of German silver, closed and pointed at one end at the junction 

 with an iron wire, and protected above this by a non-conducting sheath ; 3 and 4, a pair of 

 thermo-electric needles composed of two wires, iron and German silver, soldered together at 

 the points, and covered with an insulating varnish. 



thermometer, that the cutaneous temperature of a limb rose during 

 the contraction of its muscles. Zienissen (1857) and Bee-lard 

 (1860-61) observed the same on man. The objection that the 

 rise of temperature depends on increased flow of blood to the skin 

 may be met by saying that the skin becomes warmer, but not 

 redder, during the contraction of the subjacent muscles. Another 

 objection, that the heating may depend on the hyperaernia of the 

 muscle during its contraction, is less easily met. 



The ordinary thermometric or thermo-electric methods are used in investigat- 

 ing muscular thermogenesis. If the bulb of a highly sensitive thermometer 

 covered with a thick layer of non-conducting material (cotton-wool) to prevent 

 the dispersion of heat is applied to the human skin above the muscle to be 

 examined ; or better, if the bulb of the thermometer is inserted between the 

 muscles of the animal, it is possible to measure the alterations of temperature. 



