8 
XATURE XOTES 
tion of the spores of Peronospera, they divide themselves into a 
certain number of polyhedric portions, which in a short time 
begin to issue, one after another, by a round opening, thus con- 
stituting oval zoospores furnished with two unequal cilia, the 
shorter of these moving forward in advance of the corpuscle, the 
other dragging after it. The movement of these small bodies 
lasts for about half an hour, describing a circle, and getting 
slower and slower until they enter into a state of perfect repose. 
When it has become fixed the zoospore takes a regular spherical 
form, giving birth on one side to a slender and curved thread, 
which in water rapidly increases in length. Professor Anton 
Kerner says the spores of the potato-fungus are borne on delicate 
hyphal threads which are protruded through the stomata of 
the host plant. These threads bifurcate and the point of each 
branch swells up into a spore. These threads are highly hygro- 
scopic, and even breathing on them produces a rapid motion and 
alteration in the twisting, so that on any change in the condition 
of their environment the branches, with their hanging spores, are 
whirled hither and thither, and the spores, which are only slightly 
attached, are scattered in all directions. 
The so-called insectivorous plants exhibit very remarkable 
movements in the capture of their prey, such as Pingiiiatla, in 
which, when an insect alights on its foliage, there is seen a gradual 
involution of its leaf-margin, but it is so gradual that it takes 
some hours before the animal is enfolded, or, in the case of large 
insects, pushed into the middle of the leaf. The leaves of the 
Sundews are especially noticeable, being characterised by the 
movements performed by the tentacular hairs in response to 
a stimulus by nitrogenous matter. These movements are 
executed most conspicuously by the longest tentacles, which 
stand out radially from the edges of the leaf. First the tentacle 
bearing the gland originally irritated, with the animal’s body 
attached to it, bends inward, performing a movement similar to 
that of the hand of a watch, passing through an angle of 45° in 
two or three minutes, and an angle of go° in ten minutes. The 
other tentacles follow in succession, and in the course of one to 
three hours all the tentacles converge on the body in question, 
while, after this ceases to struggle, they straighten themselves 
and resume their original position. 
Diouaa muscipiila has rounded leaves which are furnished with 
sensitive hairs on their upper surface. When touched by an 
intruding insect, the two halves of the blade, hitherto at right 
angles, approach one another till their sharp marginal teeth are 
interlocked, and the body touching the leaf is enclosed, this 
movement taking place in from ten to thirty seconds, and the 
act is best compared to the shutting of a half-opened book. 
They finally become flat, and even so that the intervening insect, 
if soft, is crushed to pieces. Dragon-flies, if caught upon the 
upper surface of the leaf, cause the lobes to slam together. 
The stimulus acting upon the sensitive filaments of the leaf 
