Chap. XIIT.] SECRETION AND ABSORPTION. 243 



tity of animal matter, when absorbed, suffices to produce 

 these two effects. It seems hardly credible, and yet it is 

 certainly a fact, that a bit of hard-boiled white of egg, first 

 thoroughly dried, then soaked for some minutes in water 

 and rolled on blotting-paper, should yield in a few hours 

 enough animal matter to the glands to cause them to secrete, 

 and afterwards the lobes to close. That the glands have the 

 power of absorption is likewise shown by the very different 

 lengths of time (as we shall presently see) during which the 

 lobes remain closed over insects and other bodies yielding 

 soluble nitrogenous matter, and over such as do not yield 

 any. But there is direct evidence of absorption in the con- 

 dition of the glands which have remained for some time in 

 contact with animal matter. Thus bits of meat and crushed 

 insects were several times placed on glands, and these were 

 compared after some hours with other glands from distant 

 parts of the same leaf. The latter showed not a trace of 

 aggregation, whereas those which had been in contact with 

 the animal matter were well aggregated. Aggregation may 

 be seen to occur very quickly if a piece of a leaf is immersed 

 in a weak solution of carbonate of ammonia. Again, small 

 cubes of albumen and gelatine were left for eight days on a 

 leaf, which was then cut open. The whole surface was 

 bathed with acid secretion, and every cell in the many glands 

 which were examined had its contents aggregated in a beau- 

 tiful manner into dark or pale purple, or colourless globular 

 masses of protoplasm. These underwent incessant slow 

 changes of forms; sometimes separating from one another 

 and then reuniting, exactly as in the cells of Drosera. Boil- 

 ing water makes the contents of the gland-cells white and 

 opaque, but not so purely white and porcelain-like as in the 

 case of Drosera. How living insects, when naturally caught, 

 excite the glands to secrete so quickly as they do, I know 

 not ; but I suppose that the great pressure to which they are 

 subjected forces a little excretion from either extremity of 

 their bodies, and we have seen that an extremely small 

 amount of nitrogenous matter is sufficient to excite the 

 glands. 



Before passing on to the subject of digestion, I may state 

 that I endeavoured to discover, with no success, the func- 

 tions of the minute octofid processes with which the leaves 

 17 



