122 DEOSEKA ROTUNDIFOLIA. CHAP. VI. 



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 sub- 

 stances are, as far as it is known, digested by the gas- 

 tric 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 re- 

 peatedly 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 experiments. 



Fibru-elastic Tissue. We have already seen that when little 

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

 tissue, and cartilage were completely dissolved, but the fibro- 

 elastic tissue, even the most delicate threads, were left without 

 the least signs of having been attacked. And it is well known 

 that this tissue cannot be digested by the gastric juice of 

 animals.* 



Mucin. As this substance contains about 7 per cent, of 

 nitrogen, I expected that it would have excited the leaves 

 greatly and been digested by the secretion, but in this I 

 was mistaken. From what is stated in chemical works, it 

 appears extremely doubtful whether mucin can be prepared as 

 a pure principle. That which I used (prepared by Dr. Moore) 

 was dry and hard. Particles moistened with water were placed 

 on four leaves, but after two days there was only a trace of 

 inflection in the immediately adjoining tentacles. These leaves 

 were then tried with bits of meat, and all four soon became 

 strongly inflected. Some of the dried mucin was then soaked 

 in water for two days, and little cubes of the proper size 

 were placed on three leaves. After four days the tentacles 



* See, foi instance, Sshiff, 'Fhys. de Ja Digestion,' 1SG7, torn, ii 

 D. W. 



