298 DESIGN IN NATURE 



muscles indirectly Similarly and conversely, the sympathetic system of nerves distributed to the involuntary 

 system of muscles, in certain cases, influences the cerebro-spinal system of nerves and even the voluntary system of 



muscles. 



While the cerebro-spinal and sympathetic systems of nerves are, in a way, separate and distinct, they are, never- 

 theless, united structurally. They also co-operate functionally. In like manner, the voluntary and involuntary 

 system's of muscles are separate and distinct up to a point, but they run into each other through the mixed muscles, 

 so that structurally and functionally no hard-and-fast line can be drawn between the cerebro-spinal, the sympathetic, 

 and the voluntary and involuntary muscular systems. 



As the voluntary muscles may be regarded as higher developments and differentiations of the involuntary 

 muscles, so may the cerebro-spinal nervous system be regarded as a higher development and differentiation of the 

 sympathetic nervous system. 



The two nervous systems merge into each other and the two muscular systems do hkewise. With this 

 community of structure and function on the part of the nervous and muscular systems it will excite no surprise when 

 it is stated that the pale, unstriated, involuntary system of muscles, in which are included the heart,^ stomach, 

 ahmentary canal, bladder, uterus, &c., and which are characterised by rhythmic movements, have a supply of 

 cerebro-spinal and sympathetic nerves ; while the red, striated, voluntary system of muscles, in which are included 

 the diaphragm and the muscles of the chest and abdomen, but which in this case take on rhythmic movements, have 

 a supply of cerebro-spinal nerves alone. 



Here we have the cerebro-spinal system of nerves lending itself to rhythmic movements. In other words, we 

 have the highest form of muscle performing rhythmic movements, which, strictly speaking, is the function performed 

 by the lowest form of muscle (involuntary) and the lowest form of nerve (the sjinpathetic). 



This of itself breate down the distinction between the two kinds of nerve and the two kinds of muscle in 

 question. Nay more, it shows that rhythmic movements are not altogether foreign to the highest form of nerve and 

 the highest form of muscle. 



As regards the structure of muscle and of nerve it is a mere question of development and differentiation. The 

 pale, unstriated, involuntary muscle is foimd in the stomach, intestine, bladder, uterus, limgs, blood-vessels, &c. ; the 

 red striated muscle is found in the heart, the diaphragm, the muscles of the chest, and the muscles of the abdomen 

 — but all the muscles named, striated and unstriated, may and do act occasionally, involuntaril)'' and rhythmically. 

 The heart affords an example of a red striated muscle which moves involuntarily. The muscles of the pharynx 

 and larynx are partly voluntary and partly involuntary, and are known as mixed muscles. The muscles of the hmbs 

 consist of red, striated muscles, and, as a rule, act voluntarily ; they, however, imder certain circumstances, act 

 involuntarily, as in the case of lunatics and, during sleep, in sane persons. 



Similarly, what is the sympathetic system of nerves in man suffices for many of the lower animals, which have 

 no brains, but which nevertheless perform what must be regarded as a low form of voluntary movements. The five- 

 rayed star-fish is an example.^ 



If, however, the pale, unstriated, involuntary muscles culminate in the red, striated, voluntary muscles, and the 

 sympathetic system of nerves culminates in the cerebro-spinal, then the following inference may fairly be drawn — 

 all muscular movements and all nerve action are, or may be, rhythmic in character. 



All the handicrafts are dependent on muscle training. The skilled artificers in every department of labour rely 

 for their deft movements on the highly-trained voluntary muscles of their hands, arms, feet, legs, and other parts of 

 their bodies. The nicety of movement in many cases attained is truly marvellous. 



No finer study of harmony structurally or functionally can anywhere be witnessed than is presented by a f ally- 

 developed, highly-trained muscular system. The ease, the grace, the subtlety, the dignity, the power, nay, the 

 majesty of motion, is in some cases transcendent. For the highest manifestations of muscular excellence there must 

 be mind behind to give direction and expression. 



As regards the cerebrum or brain, which is the chief portion of the cerebro-spinal nervous system, it is important 

 to point out all that its actions and manifestations are of the interrupted order. Even the brain works and rests 

 at intervals. 



It would be easy to multiply indefinitely the many interesting points connected with the rhythms and reflexes 

 in the organic kingdom, and to associate them with protoplasm, with voluntary and involuntary muscles, with nerves 

 or their representatives, with the intake and output of matter in hving structures, with a Designer and Regulator 

 of the Universe, with law and order, and endless striking examples of " means to ends," and of cause and effect. It 



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 



I am aware that the majority of physiologists would attrilrate the movements of the star-fish to irritability, stimulation and reflex aetion' 



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' 



Its movements are in no sense involuntary or haphazard. ' ctitam enas. 



