Crap. IX.] SUMMARY OF THE CHAPTER. 185 
certain salts and acids affect the leaves, with respect to the 
subsequent action of the phosphate, exactly like water, whilst 
others allow the phosphate afterwards to act quickly and 
energetically. In this latter case, the interstices of the cell- 
walls may have been blocked up by the molecules of the 
salts first given in solution, so that water could not after- 
wards enter, though the molecules of the phosphate could do 
so, and those of the carbonate still more easily. 
The action of camphor dissolved in water is remarkable, 
for it not only soon induces inflection, but apparently renders 
the glands extremely sensitive to mechanical irritation; for 
if they are brushed with a soft brush, after being immersed 
in the solution for a short time, the tentacles begin to bend 
in about 2m. It may, however, be that the brushing, though 
not a sufficient stimulus by itself, tends to excite movement 
merely by reinforcing the direct action of the camphor. 
The vapour of camphor, on the other hand, serves as a 
narcotic. 
Some essential oils, both in solution and in vapour, cause 
rapid inflection, others have no such power; those which I 
tried were all poisonous. 
Diluted alcohol (one part to seven of water) is not poison- 
ous, does not induce inflection, nor increase the sensitiveness 
of the glands to mechanical irritation. The vapour acts as a 
narcotic or anwsthetic, and long exposure to it kills the 
leaves. 
The vapours of chloroform, sulphuric and nitric ether, act 
in a singularly variable manner on different leaves, and on 
the several tentacles of the same leaf. This, I suppose, is 
owing to differences in the age or constitution of the 
leaves, and to whether certain tentacles have lately been in 
action. That these vapours are absorbed by the glands is 
shown by their changed colour; but as other plants not 
furnished with glands are affected by these vapours, it is 
probable that they are likewise absorbed by the stomata of 
Drosera. They sometimes excite extraordinarily rapid in- 
flection, but this isnot an invariable result. Ifallowed to act 
for even a moderately long time, they kill the leaves; whilst 
a small dose acting for only a short time serves as a narcotic 
or anesthetic, In this case the tentacles, whether or not 
they have become inflected, are not excited to further move- 
ment by bits of meat placed on the glands, until some 
considerable time has elapsed. It is generally believed that 
