426 NUTRITION. 



oxygen are applied; the body loses, therefore, during the first eight 

 days of inanition only about l-46th part of its weight in the twenty- 

 four hours. But when cats are supplied with as much flesh as 

 they will eat, they are able to absorb such excessively large quan- 

 tities of it in the metamorphosis of matter, that the flesh they con- 

 sume amounts to l-9th, and the oxygen absorbed with it to almost 

 l-24th part of their bodily weight. 



When we compare the products of excretion yielded during a 

 scanty and an abundant supply of flesh, we find that the quantities 

 of the excretions stand in a direct relation to the amount of nourish- 

 ment, and that, consequently, the increase or diminution of the food 

 exerts no influence whatever on the proportions between the dif- 

 ferent excreta, or on their quality ; the ratio of the absorbed oxygen 

 to that in the exhaled carbonic acid, is in all cases the same, namely 

 as 100 : 79'3. The ratio between the expired carbonic acid and the 

 expired water becomes, however, changed when a larger amount of 

 animal food is taken ; thus, for instance, in one case it was found 

 that on a scanty flesh-diet 75 '6 parts of aqueous vapour were 

 expired for 100 of carbonic acid, while on an abundant flesh-diet 

 there were only 42*15 parts of water to 100 of carbonic acid; hence 

 in the latter case a relatively larger quantity of water must be 

 separated by the kidneys, as indeed Schmidts determinations have 

 also shown ; for the ratio of the perspired aqueous vapour to the 

 water excreted by the kidneys and faeces is 23*3 : 76*7 m tne former, 

 and 17*84 : 82'16 in the latter case. On a scanty flesh-diet, water 

 being at the same time withheld from the animals,the ratio of the car- 

 bonic acid to the expired aqueous vapour became so far changed that 

 for 100 parts of carbonic acid 80 parts of water were exhaled by 

 the skin and lungs, and hence in this case there was relatively less 

 water separated by the kidneys than on a scanty flesh-diet without 

 the deprivation of water. These proportions are best seen in the 

 following comparative table which we have calculated from 

 Schmidt's results. We take the flesh that was consumed (that is 

 to say, its dry residue) as the unit, and calculate the amount of 

 solid matters which pass away in the urine and faeces, the perspired 

 carbonic acid and aqueous vapour, but exclude the quantity of 

 water that has been taken and that is separated by the solid and 

 fluid excretions. I. has reference to the metamorphosis of tissue 

 when the minimum quantity of food was taken, there being at the 

 same time free access to water. II. The greatest possible quantity 

 of food and unimpeded access to water. III. A normal flesh-diet 

 (that is to say, one with which the weight of the body remains 



