114 REPORT—1874. 
either digestion or assimilation, and that these, as well as the pouring out of the 
acid fluid, are all functions of the glands. 
In what I have said, I have described the most striking instances of plants which 
seem to invert the order of nature, and to draw their nutriment (in part at least) 
from the animal kingdom, which it is often held to be the function of the vegetable 
kingdom to sustain. Pe 
I might have added some additional cases to those I have already dwelt upon. 
Probably, too, there are others still unknown to science, or whose habits have not 
yet been detected. Delpino, for example, has suggested that a plant first described 
by myself from Tierra del Fuego—Caltha dioneefolia*—is so analogous in the 
structure of its leaves to Dionea, that it is difficult to resist the conviction that its 
structure also is adapted for the capture of small insects}. 
But the problem that forces itself upon our attention is, how does it come to pass 
that these singular aberrations from the otherwise uniform order of vegetable 
nutrition make their appearance in remote parts of the vegetable kingdom? why are 
they not more frequent ? and how were such extraordinary habits brought about or 
contracted‘? At first sight the perplexity is not diminished by considering (as we 
may do for a moment) the nature of ordinary vegetable nutrition. Vegetation, as 
we see it everywhere, is distinguished by its green colour, which we know depends 
on a peculiar substance called chlorophyl—a substance which has the singular 
property of attracting to itself the carbonic acid gas which is present in minute 
quantities in the atmosphere, of partly decomposing it so far as to set free a portion 
of its oxygen, and of recombining it with the elements of water, to form those sub- 
stances, such as starch, cellulose, and sugar, out of which the framework of the 
lant is constructed. but, besides these processes, the roots take up certain matters 
from the soil. Nitrogen forms nearly four fifths of the air we breathe, yet plants 
can possess themselves of none of it in the free uncombined state. They withdraw 
nitrates and salts of ammonia in minute quantities from the ground, and from these 
they build up with starch, or some analogous material, albuminoids or protein 
compounds, necessary for the sustentation and growth of protoplasm. 
At first sight nothing can be more unlike this than a Dionea or a Nepenthes 
capturing insects, pouring out a digestive fluid upon them, and absorbing the albu- 
minoids of the animal, in aform probably directly capable of appropriation for its 
own nutrition. Yet there is something not altogether wanting in analogy in the 
case of the most regularly constituted plants. The seed of the castor-oil plant, for 
example, contains, besides the embryo seedling, a mass of cellular tissue or endo- 
sperm filled with highly nutritive substances. The seedling lies hetween masses of 
this and is in contact with it; and as the warmth and moisture of germination set 
up changes which bring about the liquefaction of the contents of the endosperm, 
and the embryo absorbs them, it grows in so doing, and at last, having taken up all 
it can from the exhausted endosperm, develops chlorophyl in its cotyledons under 
the influence of light, and relies on its own resources. 
A large mumber of plants, then, in their young condition borrow their nutritive 
compounds ready prepared ; and this is, in effect, what carnivorous plants do, more 
or less, later in life. That this is not merely a fanciful way of regarding the rela- 
tion of the embryo to the endosperm, is proved by the ingenious experiments of Van 
Tieghem, who has succeeded in substituting for the real, an artificial endosperm, 
consisting of appropriate nutritive matters}. Except that the embryo has its food 
given to it in a manner which needs no digestion (a proper concession to its in- 
fantine state), the analogy here with the mature plants which feed on organic food 
seems to be complete. 
But we are beginning also to recognize the fact that there are a large number of 
_ flowering plants that pass through their lives without ever doing a stroke of the 
work that green plants do. These have been called saprophytes. Donotropa, the 
curious bird’s-nest orchis (Neotita Nidus-avis), Epipogium, and Corallorhiza are 
instances of British plants which nourish themselves by absorbing the partially 
* Flora antaretica, vol. ii. p. 229, t. 84. 
t Ulteriori osservazioni sulla Dicogamia, parte prima, p. 16. 
t Ann. des Se. Nat. 5° sér, vol. xvii. pp. 205-224 (1873). 
