DEFINITIONS AND TECHNICAL CONSIDERATIONS. 363 



stored up to be subsequently used the next day. The amount of oxygen 

 penetrating the blood is entirely independent of the breathing; but upon the 

 volume needed for the combinations that follow, many factors have an impor- 

 tant influence, such as the kind of food eaten, the composition of the blood, 

 etc Evidently, when food consists mainly of protein substances, the number 

 of blood corpuscles is increased. The dividing up of the compounds into 

 simple forms then becomes more complicated, and the oxygen consumed is 

 greater. Experiments by Henneberg upon oxen appear to demonstrate that 

 during sleep they store up a certain amount of oxygen that is transformed into 

 carbonic acid during work. Under these circumstances we know the amount 

 of oxygen, hydrogen and carbon contained in the fodder, and the amount in 

 excrement and the amount deposited in the body. It is possible to ascertain 

 the percentage of each that was consumed in the formation of carbonic acid 

 and water that was subsequently absorbed in the body. The percentage of 

 oxygen taken from the air is determined by the use of the Pettenkofer 

 apparatus described elsewhere. Evidently a certain equilibrium between 

 night and day is, on the long run. established. It must be understood that in 

 these transformations the nutritive elements must first pass through the 

 tissues to enter the circulation and thus undergo a certain dissociation before 

 the combination with oxygen can be complete. It necessarily follows that by 

 reason of excessive work, more tissue is consumed. The oxygen demanded 

 for its burning must also increase. Naturally when the wear and tear is 

 greater than the repair, the animal gets thin. The reverse is also true, and 

 upon this fact the fattening of an animal depends. In regard to this it 

 might be pointed out that in feeding rations, frequent mistakes occur, as when 

 a poor ration follows a rich one. the falling off in fat, etc., represents more 

 money than the value of fodder saved. It takes very much less time to 

 destroy than to build up. 



The repair of wastes in the formation of new cells is a very complicated 

 question. The skin, nails, hair, etc. in other words every part of the body 

 are being gradually renewed. This wear and tear is evidently very much 

 greater with young growing animals than it is with such as are more fully 

 grown. 



The development of the bony frame is most important, and as it is com- 

 posed of saline principles, the fodder must contain those salts that are requisite 

 to repair loss. Hay and cereals of all kinds fill the required conditions. Once 

 the bones and nerves have attained their full development they undergo very 

 little change. From what has just been said, the importance of phosphates in 

 rations is evident. \Vhen an animal has attained its full development, it has 

 a tendency to deposit fat, a condition much desired in the various methods 

 of fattening. A pound of fat meat may bring twice the money upon the 

 market that a pound of lean meat from another animal would bring. Several 

 French experiments by Boussingault and others have demonstrated beyond 

 cavil that carbohydrates are most important fat formers, and when fed in ex- 

 cess of what is needed, they are deposited in the fat cells of the body. This 

 subject is discussed in full in another chapter; however, for the present, we 



