256 DESIGN IN NATURE 



so-called antagonistic muscles are not in reality opposed to each other. If this were so, the object in view, namely, 

 the moving of bones and joints, would be to a large extent or wholly defeated. It should be stated that there are 

 three kinds of co-ordination in muscular movements : — 



(a) A co-ordination as between the flexors and extensors, the pronators and supinators, and the abductors 

 and adductors respectively ; 



(b) A co-ordination as between the circumductors and other peculiar muscles ; 



(c) A co-ordination as between the muscles of the chest and abdomen, and the muscles constituting the several 

 compartments of the heart, &c. 



When the chest opens, as in inspiration, one set of muscles opens, dilates, or elongates, while another set closes, 

 contracts, or shortens. There is no forcible dragging out of supposed antagonistic muscles in the movements of the 

 chest and abdomen. In like manner, when the auricles of the mammahan heart close, contract, or shorten, the ventricles 

 of the heart open, dilate, or elongate. The movements of the auricles and ventricles occur simultaneously, but the 

 auricles do not by their closure forcibly open the ventricles, neither do the ventricles, when they close, forcibly open 

 the auricles. The movements of the auricles and ventricles, which are centrifugal and centripetal in character, are 

 spontaneous and independent of each other. If it were otherwise, the auricles and ventricles would make war 

 against each other and to no purpose. The movements of the auricles and ventricles are co-ordinated, and the object 

 in view is the transmission of the blood. 



What is said of the auricles and ventricles of the heart apphes equally to the stomach, rectum, bladder, uterus, 

 and their spliincters. When the bodies of the viscera referred to close or contract, their sphincters open or elongate. 

 Here again the closing and opening movements occur simultaneously and spontaneously. When, on the other hand, 

 the sphincters open or elongate, the bodies of the viscera close or contract. The opening movements, however, do 

 not produce the closing movements, neither do the closing movements produce the opening movements. If this 

 were so, an enormous waste of muscular energy would result. Besides, and as is well known, the muscular walls 

 of the auricles are too thin to force blood (during the systole) into the thick and practically sohd ventricles : in the 

 same way, the attenuated walls of the bodies of the other viscera named have no power to force the very narrow 

 passages or outlets of the powerful sphincters. All this is proved ahke by observation and experiment. In 

 urinating, it is possible to empty the bladder, and, shortly after, to pass a small quantity of re-accumulated urine. 

 What is passed on the second occasion cannot possibly act either as an irritant or a wedge for opening the 

 sphincter vesicae. This opens spontaneously when the body of the bladder closes. In nervous individuals, 

 under certain circumstances, such as time or other pressure, urination becomes, for the time, impossible ; all 

 efforts at expulsion being rendered futile by the sphincter vesicae refusing to open spontaneously. 



The function of the lungs, heart, and hollow viscera is to receive, contain, and transmit, at stated intervals, their 

 contents, whether gases, fluids, or sohds, but the contents do not act as irritants or stimuli and produce their own 

 expulsion. If they did, the hollow viscera could not possibly act as receivers and retainers, as, under these circum- 

 stances, the contents would be ejected before they had time to accumulate or collect. Neither do the contents act 

 from over-distending the hollow viscera, as calls to urinate, defsecate, &c., if not attended to, pass ofi. The whole 

 subject of rhythm in muscles requires to be reconsidered from a new standpoint and from a greatly extended purview, 

 and the chances are that the history of muscular action will have to be re-written. 



The most remarkable feature about the hollow viscera is not that they expel their contents at regular and 

 irregular intervals, but that they allow the contents to collect within them for longer or shorter periods without 

 producing even a trace of irritation. 



This is a view of the subject hitherto altogether overlooked. It is, however, of such paramount importance 

 that I feel called upon to direct attention strongly to it. The hollow viscera are not only transmitting and expelhng 

 organs, they are also receiving, collecting, and retaining organs. This one fact destroys of itself the prevaiUng theory 

 of inherent irritability and artificial stimulation. It also mihtates against the theory of reflex action as a factor 

 in rhythmic movements. 



The subject of muscular action (voluntary and involuntary) is very fully discussed and illustrated in other parts 

 of the work. 



There can be httle doubt that the spinal cord with its ganglia and complement of sensory and motor nerves has 

 the power, within limits, of acting with or without the brain. This double power may be explained in two ways : — ■ 



(a) By the estabhshing of a nerve-habit in the cord from the frequent repetition of certain acts involving the 

 co-operation of particular sets of ganglia, sensory and motor nerves, muscles, &c. : and 



(6) The separate and independent action of the ganglia and sensory and motor nerves of certain portions of the 

 cord. 



In the latter case, the ganglia and sensory and motor nerves of the cord perform virtually the same function 



