80 DROSERA ROTDNDIFOLIA. [Chap. VI. 



stronger. The process of digestion now conimenoe<l, so that within 

 48 hrs. from the time when the acid was given tlie four cubes were 

 not only completely dissolved, but much of the liquefied albumen 

 was absorbed. 



Experiment It. Two cubes of albumen (^ of an inch, or 

 .635 mm.) were placed on two leaves, and were treated with alkalies 

 as in the hist experiment, and with the same result; for after 22 

 hrs. they had their angles perfectly sharp, showing that the diges- 

 tive process had been completely arrested. I then wished to ascer- 

 tain what would be the effect of using stronger hydrochloric acid; 

 so I added minute drops of the strength of 1 per cent. This proved 

 rather too strong, for after 48 hrs. from the time when the acid 

 was added one cube was still almost perfect, and the other only 

 very slightly rounded, and both were stained slightly pink. This 

 latter fact shows that the leaves were injured," for during the 

 normal process of digestion the albumen is not thus coloured, and 

 we can thus understand why the cubes were not dissolved. 



From these experiments we clearly see that the secretioH 

 has the power of dissolving albumen, and we further see 

 that if an alkali is added, the process of digestion is stopped, 

 but immediately recommences as soon as the alkali is neu- 

 tralised by weak hydrochloric acid. Even if I had tried no 

 other experiments than these, they would have almost suf- 

 ficed to prove that the glands of Drosera secrete some fer- 

 ment analogous to pepsin, which in presence of an acid gives 

 to the secretion its power of dissolving albuminous com- 

 pounds. 



Splinters of clean glass were scattered on a large number 

 of leaves, and these became moderately inflected. They were 

 cut off and divided into three lots; two of them, after being 

 left for some time in a little distilled water, were strained, 

 and some discoloured, viscid, slightly acid fluid was thus 

 obtained. The third lot was well soaked in a few drops 

 of glycerine, which is well known to dissolve pepsin. Cubes 

 of albumen (^ of an inch) were now placed in the three 

 fluids in watch-glasses, some of which were kept for several 

 days at about 90 Fahr. (32*'.2 Cent.), and others at the 

 temperature of my room; but none of the cubes were dis- 

 solved, the angles remaining as sharp as ever. This fact 

 probably indicates that the ferment is not secreted until the 



* Sachs remarks (' Tniit4 de agents, allow all their colouring 



Bot.' 1874, p. 774), thnt cells matter to escape Into the sur- 



wbich are klllf>d by freezing, by rounding water, 

 too great beat, or by chemical 



