Cuap. V. EFFECTS OF ORGANIC FLUIDS. 81 
from the time when the drops were placed on the leaves, all 
four had almost re-expanded. ‘They were then given little bits 
of meat, and these acted more powerfully than the solution. 
One part of isinglass was next dissolved in 437 of water; the 
fluid thus formed was so thin that it could not be distinguished 
from pure water. The usual-sized drops were placed on seven 
leaves, cach of which thus received -4, of a grain (0295 mg.). 
Three of them were observed for 41 hrs., but were in no way 
affected; the fourth and fifth had two or three of their exterior 
tentacles inflected after 18 hrs.; the sixth had a few more; 
and the seventh had in addition the edge of the leaf just 
perceptibly curved inwards. The tentacles of the four latter 
leaves began to re-expand after an additional interval of only 
8 hrs. Hence the 53, of a grain of isinglass is sufficient to affect 
very slightly the more sensitive or active leaves. On one of the 
leaves, which had not been acted on by the weak solution, and on 
another, which had only two of its tentacles inflected, drops of 
the solution as thick as milk were placed; and next morning, 
after an interval of 16 hrs., both were found with all their ten- 
tacles strongly inflected. 
Altogether I experimented on sixty-four leaves 
with the above nitrogenous fluids, the five leaves 
tried only with the extremely weak solution of isin- 
glass not being included, nor the numerous trials 
subsequently made, of which no exact account was 
kept. Of these sixty-four leaves, sixty-three had their 
tentacles and often their blades well inflected. The 
one which failed was probably too old and torpid. 
But to obtain so large a” proportion of successful 
cases, care must be taken to select young and active 
leaves. Leaves in this condition were chosen with 
equal care for the sixty-one trials with non-nitro- 
genous fluids (water not included); and we have seen 
that not one of these was in the least affected. We 
may therefore safely conclude that in the sixty-four 
experiments with nitrogenous fluids the inflection of 
the exterior tentacles was due to the absorption of 
