Fune 1, 1871] 
NATURE 
ot 

A plant cannot assimilate pure carbon, or hydrogen, or 
nitrogen ; it seems that it can assimilate no elementary substance 
except oxygen, unless it be presented to it in the nascent condi- 
tion. An animal stands in precisely the same relation to the 
binary compounds, carbonic acid, water, and ammonia. How- 
ever abundantly, therefore, it might be supplied with these 
binary compounds which actually contain all the elements 
necessary for its sustenance, it would surely die of inani- 
tion. In order to be capable of affording nourishment to 
the animal kingdom, these substances must be elaborated to the 
condition of ternary and quaternary compounds, and this can 
only be done in the cells of plants. This, then, is the broad and 
practical distinction between the vegetable and theanimalkingdoms,. 
Plants have the power of absorbing, modifying, and organising in- 
organic substances, while animals are entirely dependent upon 
the organic substances thus prepared for their support. Taken 
in this sense, the distinction between the two kingdoms is most 
marked, and of the highest practical value; but when we set 
aside this one peculiar property, which is possessed only by some 
plants, and only by certain parts of those plants at certain periods 
of their life, and especially when we observe certain minute forms, 
of low organisation, on the verge of either kingdom, it becomes 
absolutely impossible to assign any definite distinctive character. 
The character which is, perhaps, most palpable and universal, is 
that a mass of vegetable protoplasm is at some time during its 
existence, inclosed in a cell-wall, which is composed of cellulose, 
or some very nearly allied ternary compound. Animal proto- 
plasm is rarely, if ever, confined in this way; that is to say, 
in nucleated cells, with cellulose walls, which are found in all 
plants, and are not found in the animal kingdom. 
The protoplasm of the cells of plants has the power, without 
developing colour and without the aid of light, of absorbing, 
decomposing, and assimilating the elements of already prepared 
organic ternary and quaternary products, whether they be de- 
rived from the soil or surface to which the plant is attached, as 
in the case of fungi ; or from sap already elaborated by another 
part of the same plant, as in the growing root; or even of 
another plant, as in pale parasites. Most growing points in 
plants are pale, and the protoplasm in the cells of a pale shoot, 
or of a colourless plant, has precisely the same vital powers 
and relations as animal protoplasm. It is only in cells in which 
protoplasm elaborates and incorporates with itself endochrome, 
which seems to be a more powerful catalytic agent, capable of 
disengaging the component atoms of the more stable binary com- 
pounds when loosened by the vibrations of light, that the special 
function of the vegetable cell is performed. The cells of a pale 
growing point develop the characteristic cellulose wall, but the 
supply of material is abundant, for the protoplasm of these cells 
is either confluent, through the porous cell-walls, with the pro- 
toplasm of chlorophyll cells, or, as in the seed, it is in connec- 
tion with a cache of preserved food, prepared and stored up by 
the protoplasm and endochrome of previous leaves. 
The difference between the great mass of plants, as represented 
by their familiar and higher groups, and the higher animals, is 
very palpable ; it is only among the comparatively obscure forms 
near the limits of either kingdom that a difficulty occurs. The 
general chemical composition of plants differs markedly from that 
of animals. A plant consists mainly of ternary compounds, 
cellulose, dextrine, starch, &c. In an animal, ternary com- 
pounds, although some of them—such as oils and fats—are of 
great importance in its economy, play altogether a subordinate 
part, and the bulk of the body is made up of substances of the 
albumen series—albumen, fibrin, and gelatin. Untillately this 
chemical distinction was regarded as absolute, and still it holds 
good generally, though glycogen and glucose (animal starch and 
sugar), and now recognised as being universally present in the 
tissues of the higher animals whether in health or in disease. A 
colouring matter apparently undistinguishable from chlorophyll is 
found in the green bodies of Hydra and Stentor, though there is as 
yet no evidence that this animal endochrome possesses the power 
of decomposing carbonic acid ; and cellulose, perhaps the most 
special of the vegetable products, is found in the testa of ascidians. 
Endochrome is absent in many fungi. 
The intimate structure of plants is usually very different from 
that of animals. Plants and all their parts consist of but one 
histological element, the cell with a cellulose wall, and its very 
simple modifications ; the texture of plants is therefore to a great 
degree homogeneous. Animals, on the contrary, consist of many 
tissues highly differentiated, among which the nucleated vesicle 
with a definite wall, and tissues simply derived from it, are com- 


paratively rare. The structure test fails also, however, on the 
borderland, for the most simple animals, such as Amceba and 
Gromia, are mere minute masses of jelly-like sarcode, which 
show no structure and no differentiation of tissues, and seem to 
differ only from the unicellular fungi and algze in the absence of 
the cellular wall, while the free amoebiform cell-contents of the 
myxomycetous fungi are perfectly undistinguishable from such 
animals without a knowledge of their history. 
The general plan of the organs of nutrition is strongly con- 
trasted in the two kingdoms. One of the higher plants absorbs 
its peculiar food and assimilates it by means of an enormously 
extended external surface of roots and leaves. An animal, on 
the other hand, receives its prepared nourishment into the inte 
rior of its body bya mouth, and then subjects it to complicated- 
processes of digestion and assimilation in contact with an ex- 
tended internal absorbing and secreting surface, of which special 
portions are organised for the performance of the several steps 
in the process, till at length the unassimilable residue is rejected ; 
but as we descend in the animal series, the digestive cavity be- 
comes more and more simple, and in certain undoubted animal 
forms, such as the cestoid worms, the gregarinze, and the forami- 
nifera, it is entirely wanting, and nutrition is effected by absorp- 
tion through the external surface as in plants. 
No special character can be derived from the function of re- 
production. Most plants, and many of the lower animals, are 
multiplied by gemmation and fission, and probably all animals 
and plants are propagated under certain circumstances by a 
nearly uniform process of sexual generation. The reproductive 
elements are produced internally in the higher animals and ex- 
ternally in plants; but even this minor distinction fails very 
early, for in large groups of the simpler animals ovaries and 
testes are external. 
It is true in the general sense that animals possess organs 
and functions of relation which are absent in plants. Most 
plants remain permanently rooted to the ground, and neither 
the whole plant nor any visible part of it exhibits any spon- 
taneous movements, either voluntary or automatic. It never 
performs any independent or consequent acts, from which one 
would deduce the existence of consciousness, intelligence, or 
will ; still, there are certain phenomena even among the higher 
plants, connected with the habits of climbing plants and with the 
functions of fertilisation, which it is very difficult to explain 
without admitting some low form of a general harmonising and 
regulating function comparable to such an obscure manifesta- 
tion of reflex nervous action as we have in sponges and in other 
animals in which a distinct nervous system is absent. The pro- 
toplasm in the interior of the vegetable exhibits movements so 
characteristic and special as almost to be sufficient, were other 
evidence wanting, to prove its absolute identity with the sarcode 
of the rhizopods ; and when we reach the confines of the two 
kingdoms, the test of locomotion fails like the others, for the 
branched and plant-like sponge remains permanently rooted to 
the ground, while the freed cell-contents of many of the lower 
plants move actively, either by contractility of the sarcode sub- 
stances, as in the plasmodia of the myxomycetous fungi, or by 
circlets or bunches of cilia, as in the zoospores of Volvox, 
Luglena, and Chetophora. 
If we take a water-reed from a pond in summer, and carefully 
scrape off the slimy matter adhering to it upona slip of glass 
and place it under a microscope, we may probably see in the 
field some minute oval bodies like the small seeds of a plant. 
These are the bodies of an animal belonging to the genus 
Gromia, a genus of the Rhizopoda, grouped among Haeckel’s 
Protista, but usually regarded as true animals. If we break up 
one of them under the microscope, we find it to consist of a little 
mass of apparently perfectly structureless viscid semi-fluid jelly 
inclosed in a thin membranous oval shell, with a large opening 
atone end. This gelatinous mass is under the highest powers 
destitute of anything which can be called structure. A trans- 
parent colourless matrix contains extremely small globules and fine 
granules scattered through it, and here and there are rounded 
spaces, which seem to contain a homogeneous liquid. If instead 
of breaking up the animal we allow it to remain quiet in the 
water, probably in a few minutes we see a set of very delicate 
threads protruded from the openingin the test. These threads in- 
crease in length, andspread like a branching root in the water. When 
we examine these closely, we find that they are continuous with 
the jelly of the animal, that they are, in fact, mere processes of 
that jelly. When two of the threads touch they flow together, 
and coalesce, as two streams of treacle might do, showing that 
