Omar. Xia. DROSERA BINATA. 283 
of ammonia to 218 of water (1 gr. to 2 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 Dionza and Drosophyllum. In 
this latter genus they are associated, as in the present case, with 
glands which secrete spontaneously, that is, without being 
excited. 
Drosera binatu presents another and more remarkable pecu- 
liarity, 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 sur- 
rounded by drops of viscid secretion, and they have the power of 
absorbing. This latter fact was shown by the glands imme- 
diately becoming black, and the protoplasm aggregated, when 
a leaf was placed in a little solution of one part of carbonate 
of ammonia to 487 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 presence, number, and size, 
vary on different leaves, and they are arranged rather irre- 
gularly. 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 absorbed some 
of the salt. Rather young leaves should be selected for such 
trials, for the dorsal tentacles, 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 rendered more serviceable to the 
plant; for they are not long enough to bend round the margin 
of the leaf so as to reach an insect caught on the upper surface, 
Nor would it have been of any use if these tentacles could have 
