118 DROSERA ROTUNDIFOLIA. (Cuar. VII. 
all the glands blackened. Six leaves were immersed, each in thirty 
minims (1°774. c.c.) of a solution of one part t0}4375 of water, and the 
glands were all blackened in 31 m. All six leaves exhibited some 
slight inflection, and one was strongly inflected. Four leaves were 
then immersed in thirty minims of a solution of one part to 8750 of 
water, so that each leaf received the 345 of a grain (2025 mg.), 
Only one became strongly inflected; but all the glands on all the 
leaves were of so dark a red after one hour as almost to deserve to be 
called black, whereas this did not occur with the leaves which were at 
the same time immersed in water; nor did water produce this effect 
on any other occasion in nearly so short a time as an hour. These 
cases of the simultaneous darkening or blackening of the glands from 
the action of weak solutions are important, as they show that all the 
glands absorbed the carbonate within the same time, which fact indeed 
there was not the least reason to doubt. So again, whenever all the 
tentacles become inflected within the same time, we have evidence, as 
before remarked, of simultaneous absorption. I did not count the 
number of glands on these four leaves; but as they were fine ones, 
and as we know that the average number of glands on thirty-one 
leaves was 192, we may safely assume that each bore on an average 
at least 170; and if so, each blackened gland could have absorbed only 
prion Of a grain (°00119 mg.) of the carbonate. 
A large number of trials had been previously made with solutions of 
one part of the nitrate and phosphate of ammonia to 43750 of water 
(é. e. one grain to 100 ounces), and these were found highly efficient. 
Fourteen leaves were therefore placed, each in thirty minims of a 
solution of one part of the carbonate to the above quantity of water ; so 
that each leaf received ~@5, of a grain ('0405 mg.). The glands 
were not much darkened. Ten of the leaves were not affected, cr 
only very slightly so. Four, however, were strongly affected; the first 
having all the tentacles, except forty, inflected in 47 m.: in 6 hrs. 30m. 
all except eight; and after 4 hrs. the blade itself. ‘The second leaf 
after 9 m. had all its tentacles except nine inflected; after 6 hrs. 830m. 
these nine were sub-inflected ; the blade having become much inflected 
in4hrs. The third leaf after 1 hr. 6 m. had all but forty tentacles 
inflected. The fourth, after 2 hrs. 5 m., had about half its tentacles 
and after 4 hrs. all but forty-five inflected. Leaves which were 
immersed in water at the same time were not at all affected, with the 
exception of one; and this not until 8 hrs. had elapsed. Hence there 
can be no doubt that a highly sensitive leaf, if immersed in a solution, 
so that all the glands are able to absorb, is acted on by zyq of a 
grain of the carbonate. Assuming that the leaf, which was a large one, 
and which had all its tentacles excepting eight inflected, bore 170 glands, 
each gland could have absorbed only sgeyq5 of a grain (*00024 mg.) ; 
yet this sufficed to act on each of the 162 tentacles which were 
inflected. But as only four out of the above fourteen leaves were 
plainly affected, this is nearly the minimum dose which is efficient. 
Agyregation of the Protopiasm from the Action of Carbonate of 
