on the atmosphere for their nourishment. Although the leaves at a hasty
glance do not appear green, owing to the purple colour of the
tentacles, yet the upper and lower surfaces of the blade, the pedicels
of the central tentacles, and the petioles contain chlorophyll, so
that, no doubt, the plant obtains and assimilates carbonic acid from
the air. Nevertheless, considering the nature of the soil where it
grows, the supply of nitrogen would be extremely limited, or quite
deficient, unless the plant had the power of obtaining this important
element from captured insects. We can thus understand how it is that
the roots are so poorly developed. These usually consist of only two or
three slightly divided branches, from half to one inch in length,
furnished with absorbent hairs. It appears, therefore, that the roots
serve only to imbibe water; though, no doubt, they would absorb
nutritious matter if present in the soil; for as we shall hereafter
see, they absorb a weak solution of carbonate of ammonia. A plant of
Drosera, with the edges of its leaves curled inwards, so as to form a
temporary stomach, with the glands of the closely inflected tentacles
pouring forth their acid secretion, which dissolves animal matter,
afterwards to be absorbed, may be said to feed like an animal. But,
differently from an animal, it drinks by means of its roots; and it
must drink largely, so as to retain many drops of viscid fluid round
the glands, sometimes as many as 260, exposed during the whole day to a
glaring sun. [page 19]



CHAPTER II.

THE MOVEMENTS OF THE TENTACLES FROM THE CONTACT OF SOLID BODIES.