THE COMPOSITION OF (BRASSES. 



53 



oeiit of nitrogen present in the averago albuminoid, unci by sub- 

 trai'tinir the sum of all tlioso constituents from one hundred, the 

 percentage of uiuletermined nuitter is obtaiiud, and as it of 

 course contains no nitrogen, and consists of the extractive ])rin- 

 ciples of tlu> phint, it is described as '^'itrogen free extract.' It 

 iiu'ludes all the carbo-hydrates, such a sugar, starch, and gum, 

 toirether Avith certain other allied substances, with Avhich Ave are 

 less intimately acquainted, but which have a certain nutritive 

 value. 



''Although it has been custonuiry to state as albuminoids the 

 e([uivalent of the nitrogen found, this is rarely entirely correct . 

 as a i)ortion is generally jjrescnt in a less highly elaborated form 

 of rr smaller nutritive value. This ])ortion is described as non- 

 album inoiil nitrogen, and in analysis of the ])resent day \\w 

 amount is always given as an additional source of infornuition, 

 although our knowledge of its exact value to the animal is rather 

 uncertain. 



'•'Pile wide variations in ilber and albuminoids must be regarded 

 as iieing entirely due to physiological causes, which arc dillicult to 

 explain. Diuitaria i-diiipiiiialv, for instaiu-e, which in one speci- 

 men contains the extreme amount of albuminoids and a small • 

 amount of libi'r has iiianother on'y half as much albumen and one 

 and three-quarter times as much iibi-r. AVc learn then, that 

 species are not in themselves at all tixed in their com])osition, 

 there being as large variations among specimens of the same as 

 bctAveen specimens of different species. 



Amiliixin of Phleum pratcim' (Timothy) from varlinixltHsalUkx. 

 FVIA, lU.OOM. 



