THE INFLUENCE OF FOODS ON THE BODY 271 



The heat and energy value of food has been worked out 

 by scientific men, by means of a calorimeter. This is a very 

 strong, round, hollow steel tube. A sample of a food is 

 placed in this and burned, and the amount of heat given off 

 is measured. Another instrument, called the respiration 

 calorimeter, also is used, in which a live animal is placed 

 With this the investigator can study the value of foods, and 

 can make a complete record of just what becomes of all the 

 energy produced. By means of the calorimeter, one 

 measures the heat or energy used in labor, or thrown off from 

 the body, or passed off as breath through the mouth. The 

 application of this knowledge will be found in the next 

 chapter. At the Pennsylvania experiment station there is a 

 respiration calorimeter made to hold animals as large as 

 cattle. In this there have been conducted very interesting 

 experiments on the energy value of foods as fed to cattle 

 under different conditions. 



The palatability or taste of food is considered very impor- 

 tant in feeding animals. If the food is pleasing to the taste, 

 the animal will digest it better, because the fluids used in 

 digestion will flow more freely, and thus act more completely 

 on the food. Nice sweet hay is greatly relished, while that 

 which is somewhat mouldy, or has not been properly ripened, 

 or cured, will be poorly eaten or entirely refused. The 

 animal that feeds best has a good appetite, and eats plenti- 

 fully. A great Russian experimenter, who studied the effects 

 of the appetite on the forming of the digestive fluids in dogs, 

 learned that digestion, appetite, and palatability all go 

 together. 



The use of water by the animal is very important. 

 Water may keep the entire body in a healthy condition. 

 The digestive fluids and blood need given amounts of water 

 to do their work right, and water is needed to keep the 



