920 



SPECIAL PHYSIOLOGY. 



A. Mean Results of Dietaries in oz. Avoirdupois. 



B. Average Quantities in oz. of Different Food Constituents, consumed under 

 different conditions of Best and Work (PLAYFAIR). 



The subsistence diet in Table B, is supposed to show, amongst other facts, 

 the quantity of albuminoid food consumed in the performance of the absolutely 

 essential internal mechanical work of the body, when at complete rest. Taking 

 this as a datum quantity, the additional amounts consumed in quietude, in 

 full health, in active labor, and in hard labor, are .5, 2.2, 3.5, and 4.5 oz. In 

 extreme labor, the quantity of flesh-formers, is, therefore, more than trebled, as 

 compared with the subsistence diet. The starch equivalent is also increased, 

 being, however, only doubled. This increase, Playfair considers as coincident 

 with the additional animal heat given off in increased exertion, during which 

 all the functions, digestive, assimilative, circulatory, and respiratory, are 

 much excited. An increased consumption of non-nitrogenous food is not 

 only demanded by an increased waste of the nitrogenous tissues, but it may 

 even cause the latter, by exciting the animal functions. As, for an active 

 laborer, 3.5 oz. seems to be the additional amount of albuminoid food needed 

 beyond the subsistence diet, so a horse, when at work, is said, by Playfair, to 

 consume 27 oz. more nitrogenous food than when at rest. The proportion 

 between these superadded quantities, in the Man and the horse, is about 1 to 

 7, and, as already mentioned, the horse's daily work is estimated as being 

 equal to that of 7 or 8 men. It is further stated, that the work of a horse is 

 to the work of an ox, as 1.43 to 1 ; whilst the total albuminoid food consumed 

 by those two animals, when engaged in labor, is as 1.46 to 1. In animals fed 

 exclusively upon a flesh-diet, allowance being made, when necessary, for the 

 fat contained in it, Bischoff, Pettenkofer, and Y oit, found that the carbon ex- 

 creted in the urea, is about Jth of the quantity given oft' in the form of car- 

 bonic acid ; hence Playfair supposes that 1 part of albumen, if oxidized by 

 100 parts of oxygen, may be transformed into 3.1, or about 3 parts, of urea, 

 which would contain 3 of carbon, into 21 parts of carbonic acid, which would 

 contain 21 of carbon, and into 13 parts of water. The carbon in the urea and 



