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298 DESIGN IN NATURE<br />
muscles indirectly Similarly and conversely, the sympathetic system of nerves distributed to the involuntary<br />
system of muscles, in certain cases, influences the cerebro-spinal system of nerves and even the voluntary system of<br />
muscles.<br />
While the cerebro-spinal and sympathetic systems of nerves are, in a way, separate and distinct, they are, never-<br />
theless, united structurally. They also co-operate functionally. In like manner, the voluntary and involuntary<br />
system's of muscles are separate and distinct up to a point, but they run into each other through the mixed muscles,<br />
so that structurally and functionally no hard-and-fast line can be drawn between the cerebro-spinal, the sympathetic,<br />
and the voluntary and involuntary muscular systems.<br />
As the voluntary muscles may be regarded as higher developments and differentiations of the involuntary<br />
muscles, so may the cerebro-spinal nervous system be regarded as a higher development and differentiation of the<br />
sympathetic nervous system.<br />
The two nervous systems merge into each other and the two muscular systems do hkewise. With this<br />
community of structure and function on the part of the nervous and muscular systems it will excite no surprise when<br />
it is stated that the pale, unstriated, involuntary system of muscles, in which are included the heart,^ stomach,<br />
ahmentary canal, bladder, uterus, &c., and which are characterised by rhythmic movements, have a supply of<br />
cerebro-spinal and sympathetic nerves ;<br />
while the red, striated, voluntary system of muscles, in which are included<br />
the diaphragm and the muscles of the chest and abdomen, but which in this case take on rhythmic movements, have<br />
a supply of cerebro-spinal nerves alone.<br />
Here we have the cerebro-spinal system of nerves lending itself to rhythmic movements. In other words, we<br />
have the highest form of muscle performing rhythmic movements, which, strictly speaking, is the function performed<br />
by the lowest form of muscle (involuntary) and the lowest form of nerve (the sjinpathetic).<br />
This of itself breate down the distinction between the two kinds of nerve and the two kinds of muscle in<br />
question. Nay more, it shows that rhythmic movements are not altogether foreign to the highest form of nerve and<br />
the highest form of muscle.<br />
As regards the structure of muscle and of nerve it is a mere question of development and differentiation. The<br />
pale, unstriated, involuntary muscle is foimd in the stomach, intestine, bladder, uterus, limgs, blood-vessels, &c. ; the<br />
red striated muscle is found in the heart, the diaphragm, the muscles of the chest, and the muscles of the abdomen<br />
—but all the muscles named, striated and unstriated, may and do act occasionally, involuntaril)'' and rhythmically.<br />
The heart affords an example of a red striated muscle which moves involuntarily. The muscles of the pharynx<br />
and larynx are partly voluntary and partly involuntary, and are known as mixed muscles. The muscles of the hmbs<br />
consist of red, striated muscles, and, as a rule, act voluntarily ; they, however, imder certain circumstances, act<br />
involuntarily, as in the case of lunatics and, during sleep, in sane persons.<br />
Similarly, what is the sympathetic system of nerves in man suffices for many of the lower animals, which have<br />
no brains, but which nevertheless perform what must be regarded as a low form of voluntary movements. The five-<br />
rayed star-fish is an example.^<br />
If, however, the pale, unstriated, involuntary muscles culminate in the red, striated, voluntary muscles, and the<br />
sympathetic system of nerves culminates in the cerebro-spinal, then the following inference may fairly be drawn<br />
all muscular movements and all nerve action are, or may be, rhythmic in character.<br />
All the handicrafts are dependent on muscle training. The skilled artificers in every department of labour rely<br />
for their deft movements on the highly-trained voluntary muscles of their hands, arms, feet, legs, and other parts of<br />
their bodies. The nicety of movement in many cases attained is truly marvellous.<br />
No finer study of harmony structurally or functionally can anywhere be witnessed than is presented by a f ally-<br />
developed, highly-trained muscular system. The ease, the grace, the subtlety, the dignity, the power, nay, the<br />
majesty of motion, is in some cases transcendent. For the highest manifestations of muscular excellence there must<br />
be mind behind to give direction and expression.<br />
As regards the cerebrum or brain, which is the chief portion of the cerebro-spinal nervous system, it is important<br />
to point out all that its actions and manifestations are of the interrupted order. Even the brain works and rests<br />
at intervals.<br />
It would be easy to multiply indefinitely the many interesting points connected with the rhythms and reflexes<br />
in the organic kingdom, and to associate them with protoplasm, with voluntary and involuntary muscles, with nerves<br />
or their representatives, with the intake and output of matter in hving structures, with a Designer and Regulator<br />
of the Universe, with law and order, and endless striking examples of " means to ends," and of cause and effect. It<br />
1 The heart is an exception as regards colour and striation. It affords an example of an involuntary muscle wliose fibres are red and striated<br />
I am aware that the majority of physiologists would attrilrate the movements of the star-fish to irritability, stimulation and reflex aetion'<br />
Ihis explanation does not meet the case. The star-lish controls its movements, and moves in specilic directions and to acoonmlisli np,.t'„i„ „nrls'<br />
'<br />
Its movements are in no<br />
ctitam enas.<br />
sense involuntary or haphazard.