309 UION^A MUSCIPULA. Cnir. XIU 



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 beautiful 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. Boiling 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 functions of the minute octofid processes with 

 which the leaves are studded. From facts hereafter to 

 be given in the chapters on Aldrovanda and Utricu- 

 laria, it seemed probable that they served to absorb 

 decayed matter left by the captured insects; but 

 their position on the backs of the leaves and on the 

 footstalks rendered this almost impossible. Never- 

 theless, leaves were immersed in a solution of one part 

 of urea to 437 of water, and after 24 hrs. the orange 

 layer of protoplasm within the arms of these processes 

 did not appear more aggregated than in other sped- 



