66 The Feeding of Animals 



to take up water, which transforms them to proteoses, 

 and finally to peptones, the latter being so soluble as 

 to pass through the walls of the alimentary canal into 

 the blood. These proteoses are similar to those formed 

 by the action of dilute acids, and in digestion may 

 be considered as products intermediary between the 

 original food proteids and the peptones which are the 

 final result of albuminoid digestion. The acid of the 

 stomach and the alkaline compounds in certain intesti- 

 nal juices cooperate in bringing about these necessary 

 changes, for we know that in their absence the digestive 

 ferments have no extensive action such as that de- 

 scribed. Proteoses, i. e., albumoses, globuloses, case- 

 oses, and the like, are soluble in water, are not coagu- 

 lated by boiling their solutions, and in other ways are 

 unlike the proteids from which they are derived. They 

 are regarded, however, as not having lost their albu- 

 minoid character, and, as will be shown later, they are 

 re-formed by the metabolic energy of the animal into 

 bodies similar, to those from which they take their rise. 



(5) Combinations. There are many nitrogenous 

 compounds found in plants and animals which it is 

 not possible to classify at present in any exact manner. 

 They are undoubtedly derived from simple proteids, as 

 those to which reference is made consist of albuminoids 

 united to a body of -a different kind. 



There are, first of all, certain bodies designated as 

 nucleo- albumins, this name signifying that albumin is 

 united to a nuclein, which, in its turn, is a combination 

 of an albumin with phosphoric acid. The best known 

 nucleo -albumin in agriculture is the casein of milk. 



