ARMY SURGEON AT POTSDAM 33 



After giving an historical and critical review of the facts that 

 relate to the regulated high temperature of the more perfectly 

 organized animals, which persists throughout life, and only 

 disappears with its extinction, and a table of the differences 

 of temperature in different kinds of animals, he investigates 

 the origin of animal heat. In a very interesting discussion 

 of the different views that have been held as to its nature, 

 Helmholtz states the most important results of the prevailing 

 theories in the form of the law that is fundamental to organic 

 heat, viz. that the total heat liberated by the union of two 

 or more elements to form the same compound must be the 

 same, whatever the intermediate processes through which 

 the system may have passed. But since quantity of sub- 

 stance can neither be increased nor diminished in nature, it 

 follows from the accepted theories of heat that its quantity 

 in nature must be an absolute constant, whence he concludes 

 that the actual temperature of an organism can only be due 

 to a supply of heat from without, either free or latent, and, 

 inasmuch as sources of free heat exist only in exceptional 

 cases, organic heat must necessarily be derived from the latent 

 heat of the food. The work that had been done on pro- 

 duction and loss of heat, and on animal metabolism, justified 

 the conclusion that the materials supplied to the body in 

 respiration and digestion provide the entire sum of vital warmth 

 during the successive stages of their combination within the 

 body. According to Helmholtz the only alternative is to admit 

 that organisms are the seat of a special force (the so-called vital 

 energy), by which the forces of nature can be engendered ad 

 infinitum a hypothesis that contradicts all known laws of 

 mechanical science, but cannot theoretically be objected to, 

 if physiologists choose to assume that such an incomprehensible 

 phenomenon is the distinguishing characteristic of the life- 

 process. 



In October, 1845, Helmholtz received six months' leave, in 

 order to pass the State Examination in medicine and surgery, 

 during which time he was attached as surgeon to the Friedrich- 

 Wilhelm Institute. By the terms of his engagement, he was 

 subsequently bound to serve twice this period as surgeon to 

 the King's army. On February 7, 1846, he returned to his 

 official duties with full credentials. 



