70 The Feeding of Animals 



They are soluble in water, and consequently are diffu- 

 sible throughout the plant tissues. It is believed that 

 they are the forms in which the nitrogen compounds 

 of the plant are transferred from one part to another, 

 as, for instance, from the stem to the seed. It has 

 generally been held that amides are more abundant in 

 young plants than in mature. A larger part of the 

 nitrogen of roots and tubers is found in these com- 

 pounds than in other feeding stuffs, the proportion in 

 grains being the least, and is very small indeed. Such 

 investigations as have been conducted point to the 

 conclusion that amides are not muscle -formers, as is 

 the case with proteids. This is a reason for regarding 

 the protein of coarse foods, roots, and tubers, as of 

 less value than that of the grains and grain products. 



The extractives are bodies found in the extract ob- 

 tained from beef with cold water. After the albumin 

 has been removed from such an extract by boiling, 

 these compounds known as creatin and creatinin chiefly 

 constitute the nitrogenous solids that remain. Their 

 food value is small if anything, for they appear to 

 pass through the body without change. 



