52 DEOSERA ROTUNDIFOLIA. Chap. 111. 



effect may be attributed to exosmose; for the leaves in the 

 syrup became quite flaccid, and those in the gum and starch 

 somewhat flaccid, with their tentacles twisted about in tho 

 most irregular manner, the longer ones like corkscrews. We 

 shall hereafter see that solutions of these substances, vfhen 

 placed on the discs of leaves, do not incite inflection. Particles 

 of soft sugar were added to the secretion round several glands 

 and were soon dissolved, causing a great increase of the secre- 

 tion, no doubt by exosmose ; and after 2-1 hrs. the cells showed 

 a certain amount of aggi'egation, though the tentacles were 

 not inflected. Glycerine causes in a few minutes well-pro- 

 nounced aggregation, commencing as usual within the glands 

 and then travelling down the tentacles; and this I presume 

 may be attributed to the strong attraction of this substance 

 for water. Immersion for several hours in water causes some 

 degree of aggregation. Twenty leaves were first carefully 

 examined, and re-examined after having been left immersed 

 in distilled water for various periods, with the following results. 

 It is rare to find even a trace of aggregation until 4 or 5 

 and generally not until several more hours have elapsed. 

 When however a leaf becomes quickly inflected in water, as 

 sometimes happens, especially during very warm weather, 

 aggregation may occur in little over 1 hr. In all cases 

 leaves left in water for more than 24 hrs. have their glands 

 blackened, which shows that their contents are aggregated; 

 and in the specimens which were carefully examined, there 

 was fairly well-marked aggregation in the upper cells of the 

 pedicels. These trials were made with cut-oif leaves, and it 

 occurred to me that this circumstance might influence the 

 result, as the footstalks would not perhaps absorb water quickly 

 enough to supply the glands as they continued to secrete. 

 But this view was proved erroneous, for a plant with uninjured 

 roots, bearing four leaves, was submerged in distilled water for 

 47 hrs., and the glands were blackened, though the tentacles 

 were very little inflected. In one of these leaves there was only 

 a slight degree of aggregation in the tentacles; in the second 

 rather more, the purple contents of the cells being a little 

 separated from the walls ; in the third and fourth, which were 

 pale leaves, the aggregation in the upper parts of the pedicels 

 was well marked. In these leaves the little masses of proto- 

 y)lasm, many of which were oval, slowly changed their forms 

 acd positions; so that a submergence for 47 hrs. had not killed 

 the protoplasm. In a previous trial with a submerged plant, 

 the tentacles were not in the least inflected. 



