267 



Mr. W. H. Gilburt said he had listened to Mr. White's description of the 

 Drosera leaf, and having spent some considerable time in its study, 

 perhaps a few words from him might be of use. Mr. White had referred 

 them to the back of the tentacles in order to see the spiral cells which 

 they contain, but if they would prepare the leaf properly they would have 

 no difficulty in making out the whole of its structure. The outer layers 

 of the swollen ends of the tentacles consist of a double series of thin 

 walled cells, the interior being wholly composed of the spiral cells de- 

 scribed by Mr. White. These spiral cell-groups would remind one ac- 

 quainted with leaf structure, of the groups of cells which form the free 

 terminations of the veins in most leaves ; and which were first described by 

 Herbert Spencer, and called by him absorbents. Whether they were to 

 be so regarded was difficult to say, but most authorities were doubtful on 

 the point. In the case of the Drosera, however, he thought they might 

 infer that they were not absorbents, but secreting organs — those which 

 gave out the sticky fluid. With reference to the organs which Mr. White 

 had seen, together with stomata, between the ''upstanding tentacles'" on 

 the surface, they were, he believed, the true absorbing glands of the leaf. 

 These glands are elliptical in form, divided into two along their major 

 axis. He thought, therefore, that it might be taken as correct that the 

 glands on the top of the tentacles were the secreting ones, and that the 

 sessile surface glands were the absorbents. 



Mr. Hardy enquired whether Mr. Gilburt had traced the spiral vessels 

 down into the leaf ? 



Mr. Gilburt said he had ; and regarded them as simply a continuation of 

 the vascular system of the leaf. He quite agreed with the President that 

 they had no such function as the conveyance of nutriment. 



The President said he should like to ask Mr. Gilburt whether he did not 

 think that there was a little difficulty in the way of ascribing secreting func- 

 tions to these cells ? In the general way they would find in the case of secret- 

 ing tissues that the walls were not greatly thickened, and then it was not usual 

 for a cell, which had a certain work to do, to spend itself in doing something 

 else. Was there any reason to suspect that these cells, which had their 

 walls spirally thickened, contained air ? And might they not have a 

 function of supplying air to the secreting tissues, which were possibly 

 situated in a more superficial layer of cells, so that the spiral tissue might 

 act as supporting tissue ? Of course these were merely suggestions, and 

 would weigh nothing against positive evidence. 



Mr. Gilburt said he had never seen them containing air, and they were 

 always soft and succulent. The spiral thickening was not so well marked as 

 those of spiral vessels. They were altogether so different from anything 

 else with which he was acquainted, and seeing that they contained pro- 

 toplasm more or less granular, and not air, and that the secretion was so 

 abundant, he took it that the whole structure was glandular in character. 



Mr. T. C. White said he must differ on one point from Mr. Gilburt, that as 

 to the " dewdrop " being a drop of fluid only, for by some of the means 

 which he had used he had distinctly seen a cell wall or limiting mem- 



