Cuar. XVI] MOVEMENTS OF THE LEAVES. 305 
One of the most curious facts with respect to the move- 
ment of the leaves is the short time during which they 
remain incurved, although the exciting object is left on them. 
In the majority of cases there was well-marked re-expansion 
within 24 hrs. from the time when even large pieces of meat, 
&c., were placed on the leaves, and in all cases within 48 
hrs. In one instance the margin of a leaf remained for 32 
hrs. closely inflected round thin fibres of meat; in another 
instance, when a bit of sponge, soaked in a strong infusion 
of raw meat, had been applied to a leaf, the margin began to 
unfold in 85 hrs. Fragments of glass keep the margin 
incurved for a shorter time than do nitrogenous bodies; for 
in the former case there was complete re-expansion in 16 hrs. 
30m. Nitrogenous fluids act for a shorter time than nitro- 
genous substances ; thus, when drops of an infusion of raw 
meat were placed on the midrib of a leaf, the incurved 
margins began to unfold in only 10 hrs. 37 m., and this 
was the quickest act of re-expansion observed by me; but 
it may have been partly due to the distance of the margins 
from the midrib where the drops lay. 
We are naturally led to inquire what is the use of this 
movement which lasts for so short atime? If very small 
objects, such as fibres of meat, or moderately small objects, 
such as little flies or cabbage-seeds, are placed close to the 
margin, they are either completely or partially embraced by 
it. The glands of the overlapping margin are thus brought 
into contact with such objects and pour forth their secretion, 
afterwards absorbing the digested matter. Butas the incur- 
vation lasts for so short a time, any such benefit can be of 
only slight importance, yet perhaps greater than at first 
appears. The plant lives in humid districts, and the insects 
which adhere to all parts of the leaf are washed by every 
heavy shower of rain into the narrow channel formed by the 
naturally incurved edges. For instance, my friend in North 
Wales placed several insects on some leaves, and two days 
afterwards (there having been heavy rain in the interval) 
found some of them quite washed away, and many others 
safely tucked under the now closely inflected margins, the 
glands of which all round the insects were no doubt secret- 
ing. We can thus, also, understand how it is that so many 
insects, and fragments of insects, are generally found lying 
within the incurved margins of the leaves. 
The incurvation of the margin, due to the presence of an 
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