10 MUSCULAR WORK 
The absence of definite proof in Lavoisier's experiments that animal 
heat was actually a process of combustion led to various explanations as to 
the cause of production of heat. Brodie, a working with decapitated ani- 
mals, concluded from his experiments that the brain controlled the production 
of heat, and that it was due to a nervous action rather than a chemical change. 
In this he was supported by Chossat, 6 but Hale in 1813, c Legallois in 1817, d 
Wilson Philip in 1817/ and Williams in 1835 ' found on the other hand that 
artificial respiration in decapitated animals was ample to maintain the body- 
temperature. All of these experiments, however, dealt only with measure- 
ments of body-temperature and not actually with the production of heat. 
The first important calorimetric research was that resulting from the 
offer of a prize by the Academy of Sciences in Paris for the best essay on the 
origin of animal heat. The prize was awarded to a memoir by Despretz 
published in 1824." The essay of his competitor for the prize, Dulong, was 
read before the Academy in 1822 but not published until 1841, after Dulong's 
death. A Both investigators employed essentially the same form of apparatus, 
namely, water calorimeters, and experimented with small animals such as 
rabbits and cats. According to Despretz, the heat of combustion of carbon 
and hydrogen accounted for 74 to 90 per cent of the animal heat; according 
to Dulong from 69 to 80 per cent. 1 
In 1842 appeared the first of two papers by J. R. Mayer/ the second paper 
appearing three years later in pamphlet form.* In these papers Mayer 
enunciated and elaborated the fundamental principle now known as the law 
of the conservation of energy. 
While formerly physiologists have been occupied in studying the balance 
of matter, i. e., the intake and output of the body, stimulated by the active 
researches of Boussingault l and Barral, m after the enunciation of the principle 
of the conservation of energy by Mayer, the great problem came to be one of 
the balance of energy. 
As early as Mayer's time we find physiologists considering the question of 
static work, for Mayer says: "Die Leistung eines Marines, der mit grosser 
Anstrengung ein Gewicht frei halt, oder Stundenlang unbeweglich gerade 
steht u. s. w. ist = Null; ein Gleiches, ja noch viel mehr, kann auch eine 
holzerne Figur vollbringen." 
In the light of the present tendency toward vitalism, some of Mayer's 
statements have unusual force, since he dismissed as entirely irrational the 
idea of the creation of a physical force by means of a vital force. At this time 
Liebig n advocated the existence of a vital force, and Mayer ° was particularly 
emphatic in his polemic against Liebig's theory. 
The best statement of the hold that "vitalism" had on the earlier 
a Brodie, Philosophical Transactions, 1812, 102, p. 378. 
6 Chossat, Ann. de Chim. et de Phys., 1820, ser. 2, 15, p. 37. . 
« Hale, Experiments on the production of animal heat by respiration, Boston, 1813. 
d Legallois, Ann. de Chim. et de Phys., Paris, 1817, 4, p. 21. _ 
e Wilson Philip, An experimental inquiry into the laws of the vital functions, London, 1817. 
/ Williams, Observations on the changes produced in the blood in the course of the circulation, London, 1835. 
Despretz, Ann. de Chim. et de Phys., 1824, 26, p. 337. 
» Dulong, Ann. de Chim. et de Phys., 1841, 1, p. 440. .j__ ,_\, „ 
i See Despretz's comparison of the two investigations, Ann. de Chim. et de l J nys. 1841, 2, p. 319. 
) Mayer, Ann. der Chem. u. Pharm., 1842, 42, p. 233. 
k Mayer, Die organische Bewegung in ihrem Zusammenhange mit dem btonweehsel, Heilbron, 1845. 
1 Boussingault, Ann. de Chim. et de Phys., ser. 2, 1839, 71, p. 113. Also ibid, ser. 3, 1844, 11, p. 433. 
w»Barral, Ann. de Chim. et de Phys., 1849, 26, p. 129. ■ 1Bin 
n Liebig, Die organische Chemie in ihrer Anwendung auf Physiologie und Patnologie, Braunschweig, 184^. 
Mayer, loc. cit., p. 57, et seq. 
