INFLUENCE OF FOOD. 355 



of at a different time of the day, and that this increase is both 

 relatively and absolutely greater in the colder season of the year. 

 This observation corresponds with the results yielded by the 

 experiments made by Barral* on his own person, in which he 

 found that he excreted one- fifth more carbon through the lungs in 

 winter than in summer. 



Scharling also found by his method of experiment that man 

 exhales more carbonic acid under like conditions when he has 

 eaten a full meal than when he is fasting. 



It has been proved by various experiments that the products 

 of respiration must also be influenced by the chemical nature of 

 the food. This might, indeed, have been conjectured from the 

 experiments of Dulongf and Despretz,J on the differences in the 

 respiration of herbivorous and carnivorous animals results which 

 have recently been confirmed. Dulong found that the ratio exist- 

 ing between the oxygen employed in the formation of carbonic 

 acid and the oxygen which either remained in the blood or com- 

 bined with the hydrogen, was altogether different in herbivorous 

 and in carnivorous animals, for whilst in the former there was 

 only about 1-1 Oth more oxygen absorbed than was contained in 

 the expired carbonic acid, as much as l-5th, or even the half of the 

 absorbed oxygen, was employed in the latter for other purposes 

 than that of forming carbonic acid. Lassaigne and Yvart thought 

 they had convinced themselves that guinea-pigs absorb l-5th more 

 oxygen after nitrogenous than after vegetable food. Letellier 

 found that 1000 grammes 5 weight of turtle-doves exhaled 136'5 

 grammes of carbonic acid in 24 hours when fed upon millet, 

 127*68 grammes after being fed for 3 days on sugar, and only 

 111-84 grammes of this gas after being fed for 5 days on butter. 



The experiments of Regnault and Reiset afford us still further 

 insight into these relations ; for these observers found that a 

 much larger quantity of oxygen was employed in the formation of 

 carbonic acid, when dogs had been fed on amylaceous substances 

 than when the food had been of an animal nature ; in the latter 

 case only 74'5 of every 100 parts of the absorbed oxygen were 

 found again in the carbonic acid, while in the former case 

 91 '3 parts of the oxygen were employed in the formation of 

 carbonic acid. Nitrogen was also eliminated during a vegetable 

 diet, although in far less quantity than during an animal diet. It is 



* Ann. de Chim. et de Phys. 3 SeV. T. 25, p. 165. 

 t Magendie's Journ. de Physiologie, T. 3. 

 J Ann. de Chim. et de Phys. T. 27, p. 338. 



2 A2 



