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Mr. W. Gardiner. On the Gland-Cells [Nov. 19, 



The epidermal cells of the stalk of the tentacles possess in the 

 resting condition the following structure. In each cell there is a 

 lenticular nucleus, and chlorophyll grains are present on the side of 

 the wall next tbe vascular bundle. These structures are situated in the 

 ectoplasm, and take no part in the movement of rotation. In addi- 

 tion to these a body, which is usually spindle-shaped or acicular, is 

 present in the cell, and generally occupies such a position that it 

 stretches diagonally across the cell from end to end, the two ex- 

 tremities being embedded in the cell protoplasm. I shall speak of 

 this body at present as the plastoid, on account of certain resem- 

 blances it bears as regards its microchemical reactions to plastids. 

 This name may possibly, however, not be retained. The plastoid is 

 fixed to some extent by absolute alcohol or chromic acid. With dilute 

 alcohol it swells up and disappears. With iodine it becomes dis- 

 organised and spherical. It is best fixed by watery picric acid, and 

 stains very readily and at once with Hofmann's blue. In the resting 

 stage the plastoid takes no part in the movements of the rotating 

 endoplasm. It is present in all the epidermal cells of the leaf except 

 the gland-cells and the cells immediately beneath the same, and in the 

 bending portion of those tentacles which execute movements, it is very 

 large in the cells of the convex, and very small or even apparently absent 

 in those of the concave side. In Dionsea it also occurs, being large 

 in the cells of the upper surface of the leaf, and very small in those of 

 the under. The cells themselves of the under surface in Dionsea and 

 of the concave side in Drosera are also smaller than the others of the 

 opposite side. The protoplasm of the tentacle cells is very clear 

 and hyaline, and the whole protoplasmic utricle is thin and closely 

 pressed against the cell-wall. 



Changes in the Gland-Cells during Secretion. — The cells may be made 

 to secrete by the combined stimulus of heat and moisture, by direct 

 contact, or by electrical stimulus, but especially by the stimulus of 

 food applied to the gland. 



The histological changes which occur are the following. After 

 some time (24 hours) a gland mounted in water exhibits a mottled 

 appearance, such mottling being caused by a vacuolation of the most 

 peripheral portions of the protoplasm of the gland-cells. In section 

 such a cell shows, that in the course of secretion there has been a using 

 up of the cell contents, and instead of the meshwork occupying the 

 whole of the peripheral portion of the cell, so as to give a fairly homo- 

 geneous appearance, large spherical cavities have appeared in the 

 reticulum here and there : such cavities being occupied by the cell sap. 

 The sap has, moreover, assumed a much darker pink tint, Thus a 

 breaking down or destruction of some part of the reticulum has taken 

 place. After some 72 hours' stimulation this breaking down of the 

 reticulum has reached to such an extent that in the peripheral portion 



