THE ANIMAL AS A PRIME MOVER. 325 



ordinary healthy condition, indicate, probably, a slow building of tissue 

 and construction of the gray matter constituting the brain material 

 proper, and is, perhaps, also to be taken as evidence that the organ is 

 not, lite the muscles, in the opinion of many physiologists operative by 

 the destruction of its own substance. The proportion of nutriment 

 suitable for each organ, presented by the blood, varies considerably, 

 and it maybe the fact that, for this reason at least, the volume of blood 

 sent to the brain is not a gauge of the energy supplied it in that form; 

 but the probably slow construction of the tissue of that organ, and the 

 comparatively small proportion of nerve and brain-making elements in 

 the blood, are in accord with the hypothesis that some approximation 

 to the ratio sought may be thus obtained. 



The proportion of blood flowing to the brain would make it appear 

 that about 15 per cent of the potential energy supplied the body is 

 expended in brain work. The fact that a loss of one-third the average 

 weight results in loss of power of cerebration possibly indicates that 

 one-third the brain power is devoted, in civilized races, to intellectual 

 work. The fact that life and bodily health may persist with one-third 

 the average allowance of brain would seem to show that one-third the 

 normal brain action may be required for the conduct of the purely ani- 

 mal operations of the system. The corollary of these two deductions 

 would seem to be that the normal thinker expends one-third his brain 

 power upon the vital machine, one-third upon the incidental and acci- 

 dental cerebrations of life, and one-third upon real, purely intellectual 

 work. But the size of brain and its quality are both known to be fac- 

 tors in the determination of the magnitude and nature of its product 

 intellectually, and it is very possible, probable indeed, that the intel- 

 lectual mind, with a brain well adapted to its use, not only has an 

 instrument capable of doing more and better work than the average, 

 but makes more use of that instrument than does his neighbor of equal 

 brain weight. It is for this reason, in part, that the figures here 

 assigned for brain work have been fixed upon. As a matter of simple 

 proportion, the human machine, acting as a prime mover simply, devel- 

 ops from 1,000,000 to 2,000,000 foot-pounds of work per day. The best 

 worker is, usually, also most intelligent, and, following the above sug- 

 gestion, it may, perhaps, be assumed, in default of direct measurement, 

 that the "brainless" worker — using that term in its vulgar accepta- 

 tion — may perform the lesser amount, 1,000,000 foot-pounds, and that 

 the intelligent worker may, under similar external conditions, produce 

 2,000,000 foot-pounds, and that the latter may use his brain and con- 

 sume energy supplied by the average brain in moderate amount as 

 well. If the professional brain worker does less physical labor and 

 more brain work, he may substitute the one for the other, to a consider- 

 able extent, and we have assumed 1,000,000 foot-pounds as the measure 

 of a brain worker's day's work, in addition to the labor of carrying on 

 the boddy functions and that of regular, moderate exercise. As yet, 

 however, such figures are little better than guesses. 



