NEW VIEW OF THE MECHANISM OF RESPIRATION 297 



The inspiratory and expiratory movements are fundamental and vital in their nature. The muscles are living 

 structures both in inspiration and expiration. It is not sufficient to say that the dilatation of the chest is due to vital 

 muscular acts, and that the contraction of the chest is due to passive muscular acts, to elasticity, irritability, and to 

 stimulation. The chest, as already pointed out, is said to be opened up and increased by vital acts and to be con- 

 tracted and decreased by passive elastic acts. It is further stated that the several compartments of the heart are 

 opened up and dilated by passive elastic and other mechanical acts and closed and contracted by what are 

 undoubtedly vital acts. Both statements cannot possibly be true, and the reader may rest assured that muscle does 

 not act in a certain way in one part of the body and in another and opposite way in another part of the body. This 

 one fact annihilates the mechanical theory of muscular action. 



In taking leave of the muscular respiratory rhythms I wish to explain that I am less concerned with the 

 number of muscles employed in the production of the rhythms than with the rhythms themselves, and the principle 

 which underhes muscular movements as a whole. The points which I am anxious to establish are — 



1. That not only are the respiratory movements rhythmic in character, but that they are inherent, fundamental, 

 and co-ordinated. 



2. That the movements of the diaphragm, and of the thoracic and abdominal muscles which take part in respira- 

 tion, are in all respects analogous to those occurring in the heart, stomach, bladder, and uterus. 



3. That the respiratory movements are due to the action of living muscles. 



4. That no part of the movements is referable to elasticity alone. 



5. That elasticity is a subordinate and not a leading factor in their production. 



6. That they are finely adjusted movements, which elasticity by itself could not produce. 



7. That they do not primarily owe their existence to nerve initiative. 



8. That nerves, mider certain circumstances and within limits, regulate them. 



9. That they form one of the four great organic rhythms on which hfe in the higher animals depends ; the other 

 three being the rhythms of alimentation, the circulation, and reproduction. The respiratory rhythms are vital, 

 fundamental, spontaneous, and essential to life. The respiratory muscular rhythms cause air, and the oxygen 

 it contains, to circulate within the lungs. The rhythms of the circulation cause pure and impure blood to per- 

 vade every part of the economy, so that the tissues are fed and the waste products carried off to the lungs and 

 other parts to be extruded from the system. The rhythms of alimentation bring food, drink, and nutrition 

 generally to the body, and remove from it effete matters in the shape of gases, fluids, and solids ; and the rhythms 

 of reproduction, anchored deeply in the constitution of every living being, provide for the continuation of the 

 individual and of the race. 



The four great organic rhythms hang together and are mutually interdependent. Indigestion and flatus in the 

 stomach produce palpitation and quicken the movements of the heart ; accelerated motions of the heart quicken 

 and disturb the respiratory movements ; and an impaired condition of the health dependent upon the abnormal 

 action of the ahmentary canal, heart, and limgs, impairs or destroys the sexual appetite. 



It needs little reflection to be convinced that a constant supply of atmospheric air, water, and pabulum in a 

 fluid or semi-fluid form is a prime necessity of hfe, and that the great First Cause has ensured that they shall circulate 

 within every living thing, either with or without specially-designed contrivances for the purpose. The special con- 

 trivances in the higher animals are the organic rhythms referred to. The intake and output of air, water, and semi- 

 fluid food are too important to be left to chance. They are provided for in the economy of all living things ; and 

 this one fact shows that a very high place is to be assigned to them in every form of physiological investigation. 



There is reason to believe that the movements of both the voluntary and involuntary muscles are fundamentally 

 rhjrthmic in character, and that the motor nerves distributed to both sets of muscles participate in, although they 

 do not cause, the rhythms. 



As already explained, rhythmic movements can and do take place in certain plants where neither muscular 

 fibres nor nerves exist. Similar movements occur in the heart of the chick, composed of nucleated cells, before 

 muscular fibres, nerves, or even blood make their appearance. Rhythmic movements are not, therefore, peculiar to 

 muscle and nerve. In other words, muscular fibres and nerves are not necessary for the production of rhythmic 

 manifestations. 



When, however, rhythmic movements occur in structures where both muscular fibres and nerves are present, 

 it follows that, while the rhythms inhere in the muscles, the nerves exercise a guiding or regulating power. 



In the higher animals the cerebro-spinal nervous system presides over the voluntary system of muscles — the 

 sympathetic nervous system, aided to a shght extent by the cerebro-spinal system, presiding over the involuntary 

 system of muscles. 



The cerebro-spinal system of nerves presides over the voluntary muscles directly, and over the involuntary 

 VOL. I. 2 p 



