Composition and Nutritive Value of Straw. 1 



support of respiration ; and again, gum, starch, and sugar, 

 when given to fattening beasts in excess, are transformed into 

 animal fat. There is thus no essential difference between the 

 fatty or starchy constituents of food in so far as their uses are 

 concerned, but each according to circumstances can lend itself to 

 the work which is the more peculiar province of the other. The 

 proportion of carbon in fatty matter amounts to rather more than 

 80 per cent., and is much larger than in gum, sugar, or starch. 

 Oil and fat, for this reason, are not only better producers of fat than 

 starchy and sugary compounds, but are likewise more powerful 

 agents for the support of respiration and the maintenance of animal 

 heat the heat generated in the body being proportionate to the 

 amount of carbon consumed in a given time during respiration. 

 Gum, sugar, mucilage, starch, and a few similar compounds 

 may be represented as consisting of carbon and water only, and 

 on account of the simplicity of their composition they are well 

 adapted to support respiration. The quantity of carbon con- 

 sumed by the respiration of animals varies at different times and 

 in different species, according to the rapidity of their breathing 

 and their mode of living. . Under all circumstances, however, it 

 is considerable, especially in the case of ruminating animals. 

 Thus cows consume four-ninths of the carbon contained in their 

 ordinary daily food by respiration, and throw it off in their exha- 

 lations in the form of carbonic-acid gas. Hence the absolute 

 necessity of supplying large-sized animals with abundance of 

 carbonaceous food. 



As straw contains no starch and but a small proportion of 

 gum, mucilage, and sugar, and thus is deficient in the better 

 kinds of respiratory constituents, it cannot rank high as a heat- 

 producing material, unless it can be shown that cellular and 

 woody fibre can be assimilated and used for the same purpose 

 for which starchy compounds are usually employed in the animal 

 economy. 



The question then arises and it is an important one is 

 cellular or woody fibre digestible or not? and upon a correct 

 and trustworthy answer to this question mainly depends the 

 decision whether or not straw is really as nutritious as some 

 maintain. 'To arrive at as trustworthy a reply to this question as 

 can be given in our present state of knowledge, we have to 

 inquire, in the first place, what is understood by woody fibre ? 



If any vegetable substance straw, for instance is treated suc- 

 cessively with cold and boiling water, next with alcohol and 

 ether, then with a dilute solution of caustic potash, and finally 

 with dilute sulphuric acid, an insoluble residue is obtained, 

 differing in quality and texture according to the original material 

 used in the experiment. This insoluble residue is called by 



