Cuar. I.) ACTION OF THE PARTS. 11 
varies greatly. Sometimes the apex alone, sometimes one 
side, and sometimes both sides, become incurved. For instance, 
I placed bits of hard-boiled egg on three leaves; one had the 
apex bent towards the base; the second had both distal 
margins much incurved, so that it became almost triangular 
in outline, and this perhaps is the commonest case; whilst 
the third blade was not at all affected, though the tentacles 
were as closely inflected as in the two previous cases. The 
whole blade also generally rises or bends upwards, and thus 
forms a smaller angle with the footstalk than it did before. 
This appears at first sight a distinct kind of movement, but 
it results from the incurvation of that part of the margin 
which is attached to the fuoistalk, causing the blade, as a 
whole, to curve or move upwards. 
The length of time during which the tentacles as well as 
the blade remain inflected over an object placed on the disc, 
depends on various circumstances; namely on the vigour 
and age of the leaf, and, according to Dr. Nitschke, on the 
temperature, for during cold weather, when the leaves are 
inactive, they re-expand at an earlier period than when the 
weather is warm. But the nature of the object is by far the 
most important circumstance; I have repeatedly found that 
the tentacles remain clasped for a much longer average time 
over objects which yield soluble nitrogenous matter than 
over those, whether organic or inorganic, which yield no 
such matter. After a period varying from one to seven days, 
the tentacles and blade re-expand, and are then ready to act 
again. Ihave seen the same leaf inflected three successive 
times over insects placed on the disc; and it would probably 
have acted a greater number of times. 
The secretion from the glands is extremely viscid, su that 
it can be drawn out into long threads. It appears colourless, 
but stains little balls of paper pale pink. An object of any 
kind placed on a gland always causes it, as I believe, to 
secrete more freely; but the mere presence of the object 
renders this difficult to ascertain. In some cases, however, 
the effect was strongly marked, as when particles of sugar 
were added; but the result in this case is probably due 
merely to exosmose. Particles of carbonate and phosphate 
of ammonia and of some other salts, for instance sulphate of 
zinc, likewise increase the secretion. Immersion ina solution 
of one part of chloride of gold, or of some other salts, to 487 
of water, excites the glands to largely increased secretion ; on 
