THEORETICAL CONSIDERATIONS. 55 



composition in whatever form it may be considered depends to 

 a certain extent' upon the storing up of oxygen, which remains 

 dormant as it were until needed. The Henneberg experiments 

 show that most of the oxygen is taken up during the night, this 

 being true not only when the animal is at rest, but also when 

 working. As regards carbonic acid, the reverse is true, viz., 

 most of the carbonic acid is thrown off during the day and the 

 amount increases with work done. An important fact is that 

 the storing up of oxygen seems to depend upon the amount of 

 protein fed. 



Muscular activity always means an expenditure of fat and 

 carbohydrates, hence there can be no doubt of the importance 

 of a fodder containing a sufficient supply to meet almost any 

 emergency. Additional fat is a very important element in the 

 production of work, and it is not surprising that the working 

 classes as such depend so largely upon fatty foods. This sub- 

 ject of production of work from foods has been reduced to a 

 science, and among the most important results in this special 

 direction are those of Sanson. The problem is to establish a 

 proportion between the work done in raising one kilo one meter 

 high, and the energy of a kilo of protein combined with fatty 

 substances and carbohydrates. 



The mechanical equivalent of one kilogram of protein corre- 

 sponds to 1,742,500* kilogrameters of work; and consequently 

 an animal fed can develop that amount of work without loss of 

 weight. To compose a ration that would fill all the require- 

 ments of the case, the distance traveled in a unit of time, the 

 effort consumed, and the total time during which work lasts 

 must be considered. 



If K represents foot pounds, P protein, and X the number of 



foot pounds that 1 Ib. of protein will produce, we shall have the 



j 

 following equation: K = P X X, consequently ~K = -. This 



proportion is frequently termed the mechanical coefficient of pro- 

 tein. In experiments upon horses, it was shown that by sub- 

 tracting from the protein consumed during work the protein 



*One kilo of protein = 4,100 calories; one calorie = 425 kilogrameters. 

 4,100 X 425 = 1,742,500 kg. m. 



