14 DROSERA ROTUNDIFOLIA. {Cuar. I. 
next succeeding them inwards; these then bend inwards, 
and so onwards, until the insect is ultimately carried by a 
curious sort of rolling movement to the centre of the leaf. 
Then, after an interval, the tentacles on all sides become 
inflected and bathe their prey with their secretion, in the 
same manner as if the insect had first alighted on the central 
disc. It is surprising how minute an insect suffices to cause 
this action: for instance, I have seen one of the smallest 
species of gnats (Culex), which had just settled with its 
excessively delicate feet on the glands of the outermost 
tentacles, and these were already beginning to curve 
inwards, though not a single gland had as yet touched the 
body of the insect. Had I not interfered, this minute gnat 
would assuredly have been carried to the centre of the leaf 
and been securely clasped on all sides. We shall hereafter 
see what excessively small doses of certain organic fluids 
and saline solutions cause strongly marked inflection. 
Whether insects alight on the leaves by mere chance, as a 
resting-place, or are attracted by the odour of the secretion, 
I know not. I suspect, from the number of insects caught 
by the English species of Drosera, and from what I have 
observed with some exotic species kept in my greenhouse, 
that the odour is attractive. In this latter case the leaves 
may be compared with a baited trap; in the former case 
with a trap laid in a run frequented by game, but without 
any bait. 
That the glands possess the power of absorption, is shown 
by their almost instantaneously becoming dark-coloured when 
given a minute quantity of carbonate of ammonia; the 
change of colour being chiefly or exclusively due to the 
rapid aggregation of their contents. When certain other 
fluids are added, they become pale-coloured. Their power of 
absorption is, however, best shown by the widely different 
results which follow, from placing drops of various nitro- 
genous and non-nitrogenous fluids of the same density on 
the glands of the disc, or on a single marginal gland; and 
likewise by the very different lengths of time during which 
the tentacles remain inflected over objects, which yield or do 
not yield soluble nitrogenous matter. This same conclusion 
might indeed have been inferred from the structure and 
movements of the leaves, which are’so admirably adapted for 
capturing insects. 
The absorption of animal matter from captured insects 
