454 ANIMAL PHYSIOLOGY. 
For the herbivora from 1 to 8-9 (some claim 1 to 54) is the 
estimated ratio of nitrogenous to non-nitrogenous foods: 
Nitro. Non-nitro. Nitro. Non-nitro. 
Weal iiiecausn'setangeela ees 10 1 Human milk ......... 10 37 
Hare’s flesh........... 10 2 Wheaten-flour......... 10 46 
Bef ee see yee eave eee 10 17 Oatmeal............... 10 50 
Deu tilsiscd.ccccecasgew os 10 21 Rye-meal............. 10 57 
BOARS ea jucaguisaonecieee 10 22 Barley-meal........... 10 57 
POS. cesta srdiabiecasmaes 10 23 White potatoes........ 10 86 
Mutton .............. 10 27 Blue potatoes......... 10 115 
PORK: 2 -zatincuhinccetate 10 30 RICE sycstana assed anarinteeyayanane 10 123 
Cow’s milk........... 10 30 Buckwheat-meal....... 10 180 
One investigator estimates that in order to get the one hun- 
dred and thirty grammes of proteids required by an adult man 
engaged at moderate labor, the following proportions of differ- 
ent kinds of foods must be eaten: 
Grammes. . Grammes, 
ChebS6:acccwcrewjarav cam etna 388 Wheaten bread.............. 1,444 
Littl sens cioissess caters ¢ sides oaeie. se 491 Ric@vamiasearoadeen pean 2,562 
HCAS sare s'dae alth ne wehs eas bale kas 582 Rye-bread........00eee. sees 2,875 
Beek. suiiecawhvmanss Mais.ehie 614 Potatoes... 0... .. cece en eee 10,000 
EoeSiceswieniees waueeeed as 968 
One conclusion that is most obvious from the above is that, 
in order to obtain the amount of proteids needed from certain 
kinds of food, enormous quantities must be eaten and digested ; 
and as there would be in such cases an excess of carbohydrates, 
fats, etc., unnecessary work is entailed upon the organism in 
order to dispose of this. 
FEEDING EXPERIMENTS (Ingesta and Egesta). 
If all that enters the body in any form be known, and all 
that leaves it be equally well known, conclusions may be drawn 
in regard to the metabolism the food has undergone. The pos- 
sible sources of fallacy will appear as we proceed. 
The ingesta, in the widest sense, include the respired air as 
well as the food; though from the latter must be subtracted 
the waste (undigested) matters that appear in the feces. The 
ingesta when analyzed include carbon, hydrogen, oxygen, ni- 
trogen, sulphur, phosphorus, water, and salts, their source 
being the atmosphere and the food-stufts. 
The egesta the same, and chiefly in the form of carbonic an- 
hydride, of water from the lungs, skin, alimentary canal, and 
