SPONTANEOUS MOVEMENTS IN PLANTS. 
377 
is caught the trap presently re-opens of itself, and is ready for 
another attempt. With regard to the object of this strange 
proceeding, there can be no doubt that the insect is retained 
until the softer parts of the body are completely dissolved in 
the thick mucous fluid which is exuded by the leaves : and 
Professor Asa Gray considers that the evidence is nearly com- 
plete that the animal matter is actually absorbed in the leaf 
itself. It is even stated that pieces of raw beef are digested 
by the leaf in the same manner ! Seeing, however, that it is 
now generally admitted by physiologists that even pure water 
is not absorbed through the pores of leaves, which serve only 
for the exhalation of vapour, this explanation is very hard 
of belief. The “ pitchers ” of the Nepenthes, or pitcher-plant, 
act also as fly-traps, large numbers of insects being enticed 
into them by the fluid they secrete, and are then unable to 
extricate themselves. 
The sensitiveness of the leaves of plants is but an excessive 
development of the phenomenon known as the Sleep of plants. 
In the case of the Sensitive Plant the position assumed by the 
leaf and leaflets in the night is the same as that which they 
assume when disturbed in the day-time ; and with many other 
plants, such as the clover and the Robinia or “ acacia ” tree, 
the change in the position of the leaflets, morning and evening, 
is a familiar fact. The Sleep of Plants extends also to the 
flowers, many plants opening their flowers only at particular 
times of the day. Thus the major convolvulus of the gardens 
and the goat’s-beard open at sunrise and always close by about 
noon, the evening primrose opens only in the evening, and 
many others last for but a single day. So regular is the time of 
opening and closing of some flowers, that Linnaeus drew up a 
list, which he termed a “ floral clock.” The singular part of 
the affair is, that with many flowers the time of opening and 
closing is determined, not by the degree of light, or by the 
temperature or humidity of the atmosphere, but absolutely by 
the hour of the day. The giant water-lily of the Amazons, the 
Victoria regia , opens, for the first time, about 6 p.m., and 
closes in a few hours, then opens again at 6 a.m. the next day, 
remaining open until the afternoon, when it closes and sinks 
below the water. Other plants, again, open their flowers only 
in the bright sunshine, as the beautiful yellow centaury or 
Chlora perfoliata , the sundew, Drosera rotundifolia , &c. In 
the latter plant, belonging to the same natural order as the 
Venus’s Fly-trap, and possessing a slight irritability of the 
leaves, Mr. Worthington Smith has noticed also a strong sensi- 
tiveness in the petals, the flowers closing suddenly when 
touched. 
Irritability or sensitiveness, similar to that of the leaves of 
