Ouap, VII. EFFECTS OF WATER. 139 
most, for the papille will have absorbed some small amount, 
and so will perhaps the glands of the twelve excluded tentacles 
which did not become inflected. The application of this prin- 
ciple leads to remarkable conclusions with respect to the 
minuteness of the doses causing inflection. 
On the Action of Distilled Water in causing Inflection. 
Although in all the more important experiments the dil- 
ference between the leaves simultaneously immersed in water 
and in the several solutions will be described, nevertheless it 
may be well here to give a summary of the effects of water. 
The fact, moreover, of pure water acting on the glands deserves 
in itself some notice. Leaves to the number of 141 were im- 
mersed in water at the same time with those in the solutions, 
and their state recorded at short intervals of time. Thirty-two 
other leaves were separately observed in water, making alto- 
gether 173 experiments. Many scores of leaves were also im- 
mersed in water at other times, but no exact record of the - 
effects produced was kept; yet these cursory observations sup- 
port the conclusions arrived at in this chapter. A few of the 
long-headed tentacles, namely from one to about six, were 
commonly inflected within half an hour after immersion; as 
were occasionally a few, and rarely a considerable number of 
the exterior round-headed tentacles. After an immersion of 
from 5 to 8 hrs. the short tentacles surrounding the outer 
parts of the disc generally become inflected, so that their glands 
form a small dark ring on the disc; the exterior tentacles 
not partaking of this movement. Hence, excepting in a few 
cases hereafter to be specified, we can judge whether a solution 
produces any effect only by observing the exterior tentacles 
within the first 3 or 4 hrs. after immersion. 
Now for a summary of the state of the 173 leaves after an 
immersion of 3 or 4 hrs. in pure water. One leaf had almost 
all its tentacles inflected; three leaves had most of them sub- 
inflected; and thirteen had on an average 36°5 tentacles in- 
flected. Thus seventeen leaves out of the 173 were acted on in 
a marked manner. Eighteen leaves had from seven to nineteen 
tentacles inflected, the average being 9°3 tentacles for each 
leaf. Forty-four leaves had from one to six tentacles inflected 
generally the long-headed ones. So that altogether of the 173 
leaves carefully observed, seventy-nine were affected by the 
water in some degree though commonly to a very slight degree; 
and ninety-four were not affected in the least degree. This 
