230 DROSERA BINATA. [Chap. XII. 



Bome way down the medial furrow, causing the inflection of the 

 tentacles on both sides as far as it extended. Particles of glass 

 placed on the glands in the medial furrow did not stimulate them 

 sufficiently for any motor impulse to be sent to the outer tentacles. 

 In no case was the blade of the leaf, even the attenuated apex, at 

 all inflected. 



On both the upper and lower surface of the blade there are 

 numerous minute, almost se.sile glands, consisting of four, eight, or 

 twelve cells. On the lower surface they are pale purple, on the 

 upper, greenish. Nearly similar organs occur on the footstalks, 

 but they are smaller and often in a shrivelled condition. The mi- 

 nute glands on the blade can absorb rapidly: thus, a piece of leaf 

 was immersed in a solution of one part of carbonate of ammonia 

 to 218 of water (2 gr. to 1 oz.), and in 5 m. they were all so much 

 darkened as to be almost black, with their contents aggregated. 

 They do not, as far as I could observe, secrete spontaneously; but 

 in between 2 and 3 hrs. after a leaf had been rubbed with a bit of 

 raw meat moistened with saliva, they seemed to be secreting 

 freely; and this conclusion was afterwards supported by other 

 appearances. They are, therefore, homologous with the sessile 

 glands hereafter to be described on the leaves of Dioneea and Droso- 

 phyllum. In this latter genus they are associated, as in the present 

 case, with glands which secrete spontaneously, that is, without be- 

 ing excited. 



Drosera binata presents another and more remarkable peculiar- 

 ity, namely, the presence of a few tentacles on the backs of the 

 leaves, near their margins. These are perfect in structure; spiral 

 vessels run up their pedicels ; their glands are surrounded by drops 

 of viscid secretion, and they have the power of absorbing. This 

 latter fact was shown by the glands immediately becoming black, 

 and the protoplasm aggregated, when a leaf was placed in a little 

 solution of one part of carbonate of ammonia to 437 of water. 

 These dorsal tentacles are short, not being nearly so long as the 

 marginal ones on the upper surface; some of them are so short 

 as almost to graduate into the minute sessile glands. Their pres- 

 ence, number, and size, vary on different leaves, and they are ar- 

 ranged rather irregularly. On the back of one leaf I counted as 

 many as twenty-one along one side. 



These dorsal tentacles differ in one important respect from those 

 on the upper surface, namely, in not possessing any power of 

 movement, in whatever manner they may be stimulated. Thus, 

 portions of four leaves were placed at different times in solutions 

 of carbonate of ammonia (one part to 437 or 218 of water), and all 

 the tentacles on the upper surface soon became closely inflected; 

 but the dorsal ones did not move, though the leaves were left in 

 the solution for many hours, and though their glands from their 

 blackened colour had obviously absorlMMl some of the salt. Rather 

 young leaves should be selected for such trials, for the dorsal ten- 

 tacles, as they grow old and begin to wither, often spontaneously 

 incline towards the middle of the leaf. If these tentacles had 

 possessed the power of movement, they would not have been thus 



