1885.] Stimulation of the Tentacles of Drosera dichotoma. 229 



conjectured that the molecule of hydrogen chloride is not broken 

 down in its union with ammonia to form ammonium chloride. Should 

 this conjecture not be accepted as correct, it will be necessary to seek 

 for an explanation of the phenomena observed by some relations yet 

 to be discovered. 



V. " On the Phenomena accompanying Stimulation of the 

 Gland-Cells in the Tentacles of Drosera dichotoma." By 

 Walter Gardiner, M.A„ Fellow of Clare College, 

 Cambridge, Demonstrator of Botany in the University. 

 Communicated by Professor M. Foster, Sec. R.S. -Re- 

 ceived September 5, 1885. 



(Preliminary Communication.) 



Method of Research. — Pieces of unstimulated leaves, and of leaves 

 stimulated for periods varying from 5 minutes to 72 hours, were 

 examined fresh, or after treatment with alcohol, picric acid, chromic 

 acid, or osmic acid. The most satisfactory results were obtained 

 from specimens treated for 12 hours with 1 and 2 per cent, chromic 

 acid ; such strengths dissolving the tannin .precipitate first formed, 

 and fixing the structures most successfully. The leaves were fed 

 principally upon small flies or pieces of frog muscle, since these were 

 found to succeed best. Heat stimuli, electrical stimuli, and stimulus 

 produced by contact or cutting were .also employed. 



General Histology — As regards the general histology of the ten- 

 tacles, one may notice that the gland-cells of the head are provided 

 with delicate uncuticularised Gell- walls, which are remarkably pitted 

 on their upper or free surfaces ; that the rest of the epidermal cells 

 of the tentacles have .their exterior walls excessively cuticularised and 

 resistant, and that their radial longitudinal walls are freely pitted. 



Structure of the Resting Gland-Cells. — In the typical resting gland- 

 cell, the protoplasm is arranged in a network or reticulum. The 

 meshes of this reticulum are excessively close around the nncleus, 

 which is situated at .the base of the cell, but towards the free surface 

 they are much more open ; ; the close and more open arrangement 

 merging the one into the other. The meshwork extends through the 

 whole of the cell cavity, and the interstices between the meshes are 

 occupied by the pink cell sap; the whole being bounded by the 

 ectoplasm. The gland-cells at the base of the head differ somewhat 

 in structure from the more apical. cells, as also do all the cells of the 

 short stalked tentacles which are situated at the centre of the leaf. 

 In neither of the three layers of cells covering the trache'idal cells of 

 the head could any obvious movement of the protoplasm be detected. 



