GUM. 271 



metamorphosis and solution in the lower portion of the small 

 intestine and in the large intestine, because the contents of these 

 parts in the Beaver exhibit a strongly alkaline reaction. We must 

 here also notice a conjecture, which has derived some degree of 

 support from another beautiful experiment by Mitscherlich. There 

 exists a peculiar ferment for cellulose which is generated during 

 the putrefaction of potatoes, and destroys the cellulose -cells 

 without attacking the starch. Since, moreover, it is impossible to 

 assume that the conversion of starch into dextrin and sugar by the 

 saliva and pancreatic juice can take place without a special fer- 

 ment, some probability certainly seems to attach itself to the 

 conjecture that a ferment which can decompose cellulose also 

 exists in these juices of the Beaver, and co-operates simul- 

 taneously with the alkali in the digestion of this substance. But 

 although anatomical facts, as well as chemical experiments, speak 

 in favour of the digestibility of cellulose (at least, in the case of 

 the Beaver), we cannot regard the view as perfectly proved until 

 more direct proof of its correctness can be adduced. With a 

 view of elucidating this question, I have frequently made a 

 microscopical and micro-chemical examination of the contents of 

 the small and large intestine of the Beaver, but I have unfor- 

 tunately never been able to determine with certainty that the 

 cellulose- cells obtained from thence exhibited chemical corrosion, 

 or had been converted into a starch-like substance. 



Gum is another carbo-hydrate, concerning whose uses in the 

 animal organism, notwithstanding its solubility, there is still 

 considerable doubt. Although this substance is of such rare 

 occurrence in the ordinary nutrient matters, even of the herbivora, 

 that its co-operation in the process of digestion and its appli- 

 cation to the metamorphosis of matter, can be of no great im- 

 portance, its frequent therapeutical application as a dietetic remedy 

 would entitle it to some degree of notice, even if its peculiar 

 chemical and physiological relations did not demand our attention. 

 In the obscurity which still involves the question regarding the 

 digestion of gum, three possible modes of explanation present 

 themselves ; namely, that it is converted into sugar before its 

 resorption ; that it is resorbed directly and without alteration ; or 

 lastly, that it is not at all resorbed, and is consequently completely 

 eliminated with the solid excrements. The first of these hypotheses 

 is entirely disposed of by the result of our former experiments. 

 We certainly know that gum, like other carbo-hydrates, is con- 

 verted into grape-sugar after prolonged digestion in the dilute 



