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300 DESIGN IN NATURE<br />
plant, according to others an animal, and according to a third, a half plant or a half animal. ^ This raises a question<br />
of primary importance in physiology and psychology. Is it necessary to believe that organisms devoid of a nervous<br />
system, or, at all events, of a tangible nervous system, are hopelessly ignorant of their own existence, seeing they<br />
can move in definite directions and shape their ends ? Further, are the lower animal forms (say the five-rayed star-<br />
fish), which are provided with gangha and sensory and motor nerves, but no brain, and whose movements are<br />
undoubtedly voluntary, devoid of the conscious ego ?<br />
The brain of the centipede consists of a sUght differentiation and increase of two of a longitudinal chain of<br />
gangha which occupies a central dorsal position in the body of the creature, and similar remarks may be made of<br />
the brain even of man. There is in man a striking augmentation of brain substance and brain difierentiation, but<br />
there is no breach of structural continuity as between the brain and the spinal cord, and no difference in the nature<br />
of the nervous matter ; it is a mere question of increase, elaboration, and differentiation. There is, in short, not<br />
a difference of kind, but only of degree, in nervous matter. The same is to be said of nervous and psychical<br />
manifestations in the lowest and highest animals.<br />
If, however, protoplasm can assume every variety of form and movement as apart from a tangible nervous<br />
system, it requires no great stretch of the imagination to believe that a nervous system, in the absence of a brain,<br />
discharges the essential functions of a brain ;<br />
the brain being simply a more highly developed and elaborated portion<br />
of the nervous system proper. In the lancelet {Amfhioxus lanceolatus), the lowest of the " vertebrates," there is a<br />
spinal cord but no brain (Goodsir, 1841).<br />
This line of argument militates against the exclusive possession of intellectual faculties and mind by man<br />
but, on the other hand, it accounts for a large number of facts otherwise inexphcable, namely, the voluntary and,<br />
it may be, conscious acts of the whole animal series provided with nervous systems, from man downwards. It is<br />
well known that the monkey, elephant, dog, horse, and a large number of quadrupeds reason. Similar remarks<br />
may be made of birds, and, within limits, of reptiles, fishes, spiders, ants, bees, &c. In all these cases it is mere<br />
assumption to assert that the individual is non-conscious. The words instinct, unconscious cerebration, and reflex<br />
action, do not explain the phenomena witnessed.<br />
The fact that the insectivorous plants can, by concerted, co-ordinated movements, catch insects, and digest,<br />
absorb, and assimilate them ; while the Mycetozoa can advance in search of food and retrace its steps and con-<br />
centrate on food when found, and digest and assimilate it, have further to be explained. Two explanations can<br />
be given : either the Creator works directly upon and through plants and the lower and higher animals, or aU these<br />
are provided with structures and endowments which, potentially, are equal to all the requirements of hfe, whether<br />
these be physical, mental, or psychical.<br />
The Mycetozoa have been studied to good purpose by Mr. Arthur Lister, who has skilfully summarised our<br />
knowledge of these interesting forms. He says :<br />
" They are characterised by the constant sequence of three main stages in their hfe history :<br />
"1. The firm-walled spore gives birth to a swarm-cell.<br />
"2. The swarm-cells coalesce to form a wandering plasmodium.<br />
" 3. The Plasmodium ultimately concentrates to form either sporangia, enclosing numerous spores (Endosporese),<br />
or sforofhores bearing spores on their outer surface (Exosporese).<br />
" Many species are quite common, and are found on old decaying stumps of trees and fallen branches in moist<br />
woods and shaded gardens ;<br />
others inhabit heaps of dried leaves which have lain undisturbed and become soaked<br />
with rain. The only stage in which they are conspicuous is that of the sporangia, when they appear as minute<br />
objects, some roundish, about the size of small mustard seeds, others rising in clusters of brown columns on black,<br />
hair-like stalks, while many take other characteristic forms. The different species display great variety and beauty<br />
in the colours they assume, ranging from pure white, golden yellow,<br />
purple and black.<br />
bright crimson, and iridescent violet to dark<br />
" The various phases in the life history of the group may be described as follows. The swarm-cells emerge from<br />
the spores as amoeboid bodies ; they soon acquire a flagellum at the anterior end, and creep in a linear form with<br />
the flagellum extended in advance, or swim in the surrounding water with a dancing motion occasioned by the lashing<br />
movement of the flagellum. They possess a single nucleus and a contractile vacuole. To a large extent the swarm-<br />
cells of Mycetozoa feed on bacteria, which are caught by fseudofodia projected from the posterior end of the body.<br />
The bacteria are conveyed into the body-substance, where they are digested in vacuoles which form round them.<br />
There may be one or more digestive vacuoles, each containing several bacteria at one time. The swarm-cells rapidly<br />
1 Mr. Saville Kent supports the auimality view, and traces a connection between the Mycetozoa and the Spongidte ; tlie resemblance extending<br />
to the fission or aniceliic stage, to the production in both of spoi'es with flagella or cilia of some kind, to the encysted or resting hibernating<br />
condition, and to the presence in both of rudimentary skeletons in the sha])e of horn-like elements or keratose, and spicule-like bodies of carbonate<br />
of lime.