200 DIGESTION OF CARBOHYDRATES 



cellulose ingested in vegetables and fruits is digested in the 

 human canal, in habitual constipation as much as 80 per 

 cent. The proposal to use it as a substitute for the ordinary, 

 readily-resorbed carbohydrates in cases of severe diabetes 

 is related to the assumption (which, as we will see later, is 

 not yet satisfactorily proven) that cellulose undergoes a 

 cleavage into sugars in full analogy to starch, but much 

 more slowly than the latter. 19 



Determination of Cellulose. The differences of opinion 

 upon the availability of cellulose in the body are partly to be 

 ascribed to the unsatisf actoriness of the methods used for its 

 quantitative estimation. The commonly used method of 

 Lange is based upon the unconfirmed proposition that cel- 

 lulose is not acted upon by caustic alkali. The practice of 

 Simon and Lohrisch, in which the material under examina- 

 tion is heated with 50 per cent, solution of caustic soda and 

 then decolorized with peroxide of hydrogen is attended by 

 great losses, according to Scheunert. 20 The latter author 

 recommends that the substance to be examined be first heated 

 with a highly concentrated sodium hydrate solution and the 

 undissolved residue washed well on a hardened filter, and 

 finally weighed. The ash of the cellulose thus obtained must 

 eventually be taken into consideration. 



Cytases. How is the digestion of cellulose accomplished? 

 One naturally at once assumes that the organism of the vege- 

 tarian can furnish ferments especially adapted for the 

 cleavage of cellulose just as it produces ferments for the 

 splitting of protein, sugar and fat. And for the lower forms 

 of animals an experimental foundation has been found for 

 this assumption. The brilliant researches of Biedermann 21 



19 H. Lohrisch (Med. Clinic, Halle), Zeitschr. f. exper. Pathol., 5, 478, 1909; 

 F. Moeller (Med. Clinic, Halle), Inaug. Dissert., Halle, 1911, and Intern. Beitr. 

 z. Pathol. u. Therap. d. Ernahrungsstorungen, 1, 325, 1910; F. Schilling, Arch. 

 f. Verdauungskr., 16, 720, 1910; W. Biedermann, Handb. d. vergl. Physiol., 2', 

 1315, 1911. 



W A. Scheunert, Handb. d. biochem. Arbeitsmeth., 3, 277-280, 1910; W. 

 Grimmer and A. Scheunert, Berlin, tierarztl. Wochenschr., 1910, No. 7. 



21 W. Biedermann and P. Moritz, Pfliiger's Arch., 73, 219, 1898. 



