268 Mary Davies Swartz, 



Digestion and Utilization of Cellulose by Animals. 



The literature on the digestion of cellulose up to 1909 has been so 

 exhaustively reviewed by Lohrisch that it is unnecessary to enter into 

 a detailed discussion of it. From tables (55) showing the results of 

 all previous experiments on the utilization of crude fiber in herbivora, 

 carnivora, and birds, it appears that in the case of herbivora, especi- 

 ally ruminants, 20-28 per cent of the crude fiber ingested with food 

 disappears from the alimentary canal; that in case of carnivora^ and 

 birds^ there is no utilization whatever. Lohrisch (56) himself reported 

 three experiments in which dogs were fed pure cellulose and digested 

 31.1 per cent, 37.45 per cent and 5.4 per cent respectively, but Scheu- 

 nert and Lotsch (72) repeating Lohrisch's work with a somewhat dif- 

 ferent method of determining cellulose found that the administration 

 of 40 grams of prepared white cabbage, containing 7.37 grams of pure 

 cellulose, resulted in the recovery of the total amount ingested. Cook- 

 ing the cabbage in bouillon did not increase its digestibility. They 

 attribute the apparent utilization in the preceding experiment to des- 

 truction of cellulose by the reagents used for its purification. Since 

 the publication of their paper, Lohrisch has repeated his work with 

 the dog (57), and reports complete recovery of the cellulose fed. He 

 explains the error in the earlier investigation as due to the fact that" 

 the ingested cellulose was twice subjected to purification (before feed- 

 ing and in faeces) with consequent increase in percentage of loss, 

 which was not taken into account. He points out the inevitable loss 

 of some cellulose by any method at present in use for its determina- 

 tion, and defends his own as sufiiciently accurate for all practical pur- 

 poses if conditions are carefully observed.^ 



^The only experiments on record are by Voit and Hoffmann on the dog and by 

 \'on Knieriem on the hen. 



^Experiments by Weiske on the goose, and by von Knieriem on the hen. 



'Lohrisch used the method of Simon and Lohrisch, in which the cellulose is dis- 

 solved by heating for an hour on a water bath with 50 per cent potassium hydroxide, 

 then adding f cc. of 30 per cent hydrogen peroxide, and digesting from § to f hour 

 longer if necessary. The cellulose is then precipitated by adding to the solution 

 one half its volume of 96 per cent alcohol and 6-7 cc. of concentrated acetic acid; 

 filtered off, washed with water, dilute acetic acid, alcohol and ether, dried and 

 weighed. 



Scheunert and Lotsch mix the substance to be analyzed with 100 cc. of cold water, 

 add 100 grams of potassium hydroxide and heat for an hour on a water bath, then 

 filter through a hard filter paper, wash the residue on the paper with boiling water 

 till only a trace of alkali remains, transfer it to a beaker and thence to a weighed 



