FOODS ANIMAL PRODUCTION. 75 



part in the production of liydrocarbons. In fact, it appears that the 

 protein can have taken only an exceedingly small part in the production 

 of hydrocarbons. It is shown by the results not only ihat the diges- 

 tion of cellulose in the stomach and intestines resulted in the giving 

 oft" of gaseous carbon in uuoxidized condition, as Tap]»einer found, but 

 also that this took place in the digestion of starch and the other nitro- 

 gen-free constituents in very nearly the same degree as in the case of 

 cellulose. Since, according to this, the digestion of cellulose forms no 

 exception to that of the nitrogen-free extract in general, the separation 

 of carbon in the form of hydrocarbons in itself is believed to be no 

 ground for considering cellulose of less nutritive value than starch and 

 the other carbohydrates, and still less reason for questioning the nutri- 

 tive value of cellulose in general. 



Whether the increase in the amount of hydrocarbons given oft" in 

 proportion to the increase of nitrogen-free extract in the food is a re- 

 sult of the fermentation by which the cellulose is dissolved, or a result 

 of the action of other microorganisms, is a question which can not be 

 definitely answered by experiments like the above. With the addi- 

 tion of starch meal to the food there was invariably an absolute in- 

 crease in the excretion of hydrocarbons. There is, therefore, no ground 

 for assuming that this increase depended indirectly** on the action 

 of the starch and was attributable to the after fermentation of a 

 part of the cellulose which, on account of the presence of the starch, 

 was prevented from being digested by the action of enzymes higher up 

 in the intestines. There is more ground for connecting this increased 

 excretion of hydrocarbons directly with the digestion of the starch. 



From a review of the data obtained when starch was added to the 

 ration, assuming that starch and cellulose have the same elementary 

 composition and hence are of equal value for the production of hydro- 

 carbons, it is shown that the digestion of 12,950 gm. of starch resulted 

 in the production of 385.9 gm of carbon in the form of hydrocarbons, 

 equivalent to 6.7 per cent of the carbon in the starch. 



The results are believed to afford considerable support to the theory 

 that the various components of the nitrogen-free extract do not differ 

 very materially with reference to the production of hydrocarbons. 



The question as to whether the fat in the food yields hydrocarbons 

 in its changes in the intestines could not be determined in this investi- 

 gation, since the rations fed were purposely made poor in fat and the 

 amount of digested fat was so small that its influence on the produc- 

 tion of hydrocarbons, if any, was too slight to be studied. 



Formation of glycogen in the animal body after consuming 

 xylose, J. Frentzel [Pflilger's Arch. Phy.siol., 56, No. 6 and 7, pp. 

 273-288).— T\xQ experiments of Cremer^ and Salkowski^ had indicated 

 that xylose and arabinose favored the formation of glycogen when fed 



' Ztschr. Biol., 29, p. 484. 

 «Centbl. med. Wiss., 1893. No. 11. 



