PHILOSOPHICAL SOCIETY OF WASHINGTON. 341 



gives the relative working value of the two machines. From 

 this comparison, made from experiments on soldiers in Germany 

 and France, it is found that the human machine in consuming 

 the same amount of carbon, does four and a half times the 

 amount of work of the best Cornish engine." 



" There is however one striking difference between the animal 

 body and the locomotive machine, which deserves our special 

 attention ; namely the power in the body is constantly evolved 

 by burning (as it were,) parts of the materials of the machine 

 itself; as if the frame and other portions of the wood-work of the 

 locomotive were burnt to produce the power, and then imme- 

 diately renewed. The voluntary motion of our organs of speech, 

 of our hands, of our feet, and of every muscle in the body, is 

 produced not at the expense of the soul but at that of the ma- 

 terial of the body itself. Every motion manifesting life in the 

 individual, is the result of power derived from the death as it 

 were of a part of his body. We are thus constantly renewed 

 and constantly consumed ; and in this consumption and renewal 

 consists animal life."* 



Seven years after the publication of this highly original and 

 suggestive exposition, (whose topics and line of discussion had 

 been distinctly formulated and sketched out more than two years 

 before, at the commencement of the series in 1855,) the eminent 

 physiologist Dr. Carpenter produced his valuable memoir on the 

 Conservation of Force in Physiology; in which he for the first 

 time distinctly aflfirms the development of vegetative reproductive 

 energy, by the partial running down of matter to its stabler 

 compounds, — " by the retrograde metamorphosis of a portion of 

 the organic compounds prepared by the previous nutritive ope- 

 rations :" and also the ultimate return by decay, of the whole 

 amount of force as well as of matter, temporarily borrowed from 

 nature's store. Likewise with animal powers, " these forces are 

 developed by the retrograde metamorphosis of the organic com- 

 pounds generated by the instrumentality of the plant, whereby 

 they ultimately return to the simple binary forms (watei*, car- 

 bonic acid, and ammonia,) which serve as the essential food of 

 vegetables. . . Whilst the vegetable is constantly engaged 



(so to speak) in raising its component materials from a lower 

 plane to the higher, by means of the power which it draws from 

 the solar rays, — the animal whilst raising one portion of these to 



* Agricultural Report for 1857, pp. 445-449. This important essay it 

 will be observed, antedates Prof. Joseph Le Conte's jtaper " On the Corre- 

 lation of Physical, Chemical, and Vital Force," read before the American 

 Association at Springfield, Aug. 1859, (^Proceed. Am. Assoc, pp. 187-203: 

 and Sill. Am. Jour. Sci. Nov. 1859, vol. xxviii. pp. 305-319,) as vfell as 

 Dr. Carpenter's second and more mature paper "On the application of 

 the Principle of Conservation of Force to Physiology," published in 

 Crookes' Quarterly Jour udl of Science, for Jan. and April, 1864, (vol. i. pp. 

 76-87 ; and pp. 259-277.) 



115 



