DigestuyOj Respiration arid Oalorimetry. 33 



at other times the enclosed subject is kept as nearly in perfect 

 rest aa possible, with or without a normal food supply. These 

 studies, necessarily difficult, are not only interesting but important 

 in farthering our knowledge of the laws of nutrition. 



The respiration apparatus has been used for the study of the 

 formation of fat and the decomposition of the nitrogenous com- 

 ponents of the body. Used in connection with weighings and 

 analyses of food, water, and the solid and liquid voidings, the 

 chemist is able to determine accurately what becomes of the nutri- 

 ents fed to the animals under trial and the waste products given 

 off by them, thereby measuring the effect of any given ration. 



55. An illustration. — The following example, taken from one of 

 the earlier experiments by Henneberg* at the "Weende Station, 

 will illustrate the manner of studying the formation of flesh and 

 fat in the body of the ox by means of the respiration apparatus 

 and digestion experiments. 



The animal experimented on was a full-grown ox, which 

 weighed 1,570 pounds when placed in the respiration chamber. 

 It was fed the following ration: 11 pounds of clover hay, 13.2 

 pounds of oat straw, 8.2 pounds of bean meal, 2.13 ounces of 

 salt, and drank on the average 123.7 pounds of water daily. 

 The results of one day's trial, arranged to assist the student in 

 understanding the workings of this method of investigation, are 

 here presented: 



« Neue Beitrage, Gottingen, 1870, 1, p. xix; Krafft, Lehrb. d. Landw., 

 Ill, p. 17. 

 3 



