140 PLANTS WHICH EXHIBIT MOVEMENTS IN THE CAPTURE OF PREY. 
die altogether, or are buried in the snow, retaining their green colour, but suspend- 
ing all movement and vital activity for from eight to ten months. The first snow 
falls in the districts inhabited by Bartsia invariably before the ground is frozen, 
and the wintry covering of snow, which gets deeper and deeper as time goes on, 
protects the earth so completely from the cold that even in the superficial strata 
the temperature does not sink below freezing point. In the bed thus kept free 
from frost neither vegetable nor animal life is quite torpid, and there can be no 
doubt that it is only beneficial to Bartsia, during the long interval, for its subter- 
ranean buds to obtain an abundance of food from the bodies of captured Infusoria. 
The advantage is the more obvious when one considers that the above-ground stem, 
with its foliage-leaves and flowers, has to be built up in two or three weeks, in the 
ensuing vegetative period, from the organic compounds stored in the cells of the 
scales of the subterranean buds, and that both the damp ground in which Bartsia 
grows, and also the roots of the marsh-plants to which it is joined by a few suckers, 
though yielding water and mineral salts, afford but little material for the produc- 
tion of nitrogenous compounds. 
CARNIVOROUS PLANTS WHICH EXHIBIT MOVEMENTS IN THE CAPTURE 
OF PREY. 
We have taken Lathrea and Bartsia as types of the last group of that section 
of carnivorous plants which manifest no external visible movement in the pitfalls 
for the purpose of capture or digestion. The second section, now to be discussed, 
includes plants in which movements of the leaves, or parts of leaves, modified as 
organs of seizure and digestion, take place as a result of the contact of animal 
bodies—movements which have the common object of bringing about the digestion 
of the animals, whilst the retention of the latter is effected in very various ways. 
Since in Lathrea and Bartsia the leaves, modified as organs of capture, 
exhibit no kind of motion themselves, though movements take place in the proto- 
plasm of the capitate pairs of cells in the interior of the cavities, having as their 
object the holding of the prey, these plants form, to a certain extent, a link 
between the first and second sections. All these divisions are for that matter 
merely artificial, and it is not impossible that fresh forms may be discovered and 
recognized as intermediate between the groups and series here distinguished, 
obliterating the boundaries which have been adopted by us, simply with a view to 
obtaining a general survey of the subject. 
The first group of carnivorous plants which perform movements for the capture 
of prey is composed of the various species of the genus Pinguicula (Butterwort). 
Of this stock nearly forty species are known; and they are all much alike. Scarcely 
any difference would be detected by an ordinary person between Pinguwicula 
calyptrata from the mountains of New Granada and Pinguicula vulgaris from 
our own hills. In respect of habitat, too, they exhibit close conformity. In both 
the Old World and the New they only thrive on damp spots, the neighbourhood of 
