XX 



THE COPLEY MEDALIST OF 1871 



DR. JULIUS ROBERT MAYER was educated for 

 the medical profession. In the summer of 1840, 

 as he himself informs us, he was at Java, and 

 there observed that the venous blood of some of his pa- 

 tients had a singularly bright red color. The observation 

 riveted his attention; he reasoned upon it, and came to 

 the conclusion that the brightness of the color was due to 

 the fact that a less amount of oxidation sufficed to keep 

 up the temperature of the body in a hot climate than in a 

 cold one. The darkness of the venous blood he regarded 

 as the visible sign of the energy of the oxidation. 



It would be trivial to remark that accidents such as 

 this, appealing to minds prepared for them, have often led 

 to great discoveries. Mayer's attention was thereby drawn 

 to the whole question of animal heat. Lavoisier had as- 

 cribed this heat to the oxidation of the food. "One great 

 principle," says Mayer, "of the physiological theory of 

 combustion, is that under all circumstances the same 

 amount of fuel yields, by its perfect combustion, the 

 same amount of heat; that this law holds good even for 

 vital processes; and that hence the living body, notwith- 

 standing all its enigmas and wonders, is incompetent to 

 generate heat out of nothing." 



But beyond the power of generating internal heat, the 



(451) 



