100 DROSERA ROTUNDIFOLIA. [Chap. VI. 



absorbed which was either actually poisonous or of too stimulating 

 a nature. The particlea were much more softened than those kept 

 for the same time in water, but, judging by tlie eye, very little 

 reduc(Hl in bulk. Dr. Sanderson tried tliis substance with artifu-ial 

 digestive fluid, in the manner described under globulin, and found 

 that whilst 1.31 of fibrin, only 0.456 of the hsenuitin was dissolved 

 in an hour; but the di.ssolution by the secretion of even a less 

 amount would account for its action on Drosera. The residue left 

 by the artificial digestive fluid at first yielded nothing more to it 

 during several succeeding days. 



Substances which are not Digested by the Secretion. 



All the substances hitherto mentioned cause prolonged 

 inflection of the tentacles, and are either completely or at 

 least partially dissolved by the secretion. But there are 

 many other substances, some of them containing nitrogen, 

 which are not in the least acted on by the secretion, and 

 do not induce inflection for a longer time than do inorgan- 

 ic and insoluble objects. These unexciting and indigest- 

 ible substances are, as far as I have observed, epidermic 

 productions (such as bits of human nails, balls of hair, 

 the quills of feathers), fibro-elastic tissue, mucin, pepsin, 

 urea, chitine, chlorophyll, cellulose, gun-cotton, fat, oil, and 

 starch. 



To these may be added dissolved sugar and gum, diluted 

 alcohol, and vegetable infusions not containing albumen, for 

 none of these, as shown in the last chapter, excite inflection. 

 Now, it is a remarkable fact, which affords additional and 

 important evidence, that the ferment of Drosera is closely 

 similar to or identical with pepsin, that none of these same 

 substances are, as far as it is known, digested by the gastric 

 juice of animals, though some of them are acted on by the 

 other secretions of the alimentary canal. Nothing more 

 need be said about some of the above enumerated substances, 

 excepting that they were repeatedly tried on the leaves of 

 Drosera, and were not in the least affected by the secretion. 

 About the others it will be advisable to give my experi- 

 ments. 



Fihroelnstic Tissue. We have already seen that when little 

 cubes of meat, &c., were placed on leaves, the muscles, areolar 

 tissue, and cartilage was completely dissolved, but the fibro-elastic 

 tissue, even the most delicate tbreadsj were left without the least 



