PROTOPLASMIC, AMCEBIC, AND OTHER MOVEMENTS 319 



the partly digested food (chyme) is being passed at intervals into the small intestine. The movements of the 

 stomach and its sphincters are co-ordinated, rhythmic wave movements. 



The reader will get a good idea of the structure of the oesophagus, duodenum, and human stomach — especially 

 the sphincters of the latter — from careful drawings made by me from my original dissections, preserved in the 

 Royal College of Surgeons of England, London. {Vide Fig. 67, p. 326.) 



Arrangements similar to those described in the stomach obtain in the bladder. This viscus is provided with 

 a powerful sphincter at its neck or depending portion. It completely occludes the urinary passage ; so much so, 

 that not a drop of urine can escape. When the period for micturition arrives the sphincter vesicae opens or relaxes 

 of its own accord ; the body of the bladder contracts simultaneously and rhythmically, and the urine is expelled. 

 These acts are consentaneous, but they are independent. The one does not cause the other. They are rhythmic 

 wave movements, and are means to ends, and, as such, imply pre -arrangement and design. Neither in the case of 

 the stomach nor the bladder could the practically impervious passages of the sphincters be forced. The same 

 is true of the rectum and uterus in defsecation and parturition. The sphincters ani open when the rectum closes 

 or contracts ; the cervix and os uteri open when the uterus contracts. The object of the double movement is to 

 expel the faeces and the foetus. The contents of the viscera play a merely nominal and passive part in the rhythmic 

 wave movements referred to. They do not cause them. The peculiarity of the hollow viscera (heart, stomach, 

 bladder, rectum, and uterus) is that they are containing and retaining as well as propeUing and discharging organs. 

 The double function necessitates the condition of partial rest when the organs are receiving and accommodating 

 their appropriate charges, and active alternating rhythmic movements as between the several parts of the organs 

 when their contents are being expelled. The contents are discharged in each case by the alternate opening and 

 closing rhythmic wave movements. 



It should be explained that the involuntary muscles have no origins and insertions, as is the case in the voluntary 

 muscles. They are, however, capable of very powerful action, and display what must be regarded as fundamental 

 centrifugal and centripetal movements. The centripetal and centrifugal movements furnish the types for all muscular 

 action, whether involuntary or voluntary. 



The manner in which the involuntary muscles (blood-vessels, heart, stomach, &o.), the voluntary muscles 

 (flexors, extensors, abductors, adductors, pronators, supinators, &c.), and the sarcous elements composing both act, 

 will be readUy understood by a reference to Plates Ixxxiii., Ixxxiv., and Ixxxv. which follow. 



PLATE LXXXIII 



Plate Ixxxiii. shows that voluntary muscular fibres and fibrillae may be divided longitudinally and transversely 

 and broken up into little squares or cubes (sarcous elements) ; how the double cleavage gives rise to the markings 

 and striations so well seen under high powers of the microscope ; how the sarcous elements have the power of 

 changing shape centripetally and centrifugally in two directions, namely, transversely and longitudinally ; how 

 muscles and the parts thereof (sarcous elements) move spontaneously and harmoniously in waves ; how the several 

 parts of muscles move simultaneously, one part moving transversely when the other is moving longitudinally, and 

 vice versd ; how the several parts alternately change places, there being no such thing as antagonism in muscular 

 action either as regards the sarcous elements of individual muscles, or as regards the so-called flexor and extensor 

 muscles of the body as a whole. 



The sarcous elements of the involuntary muscles are less differentiated than those of the voluntary ones. They, 

 however, act in essentially the same way. It is easy to understand how, according to my theory, parts are extended 

 and flexed, how bones and other structures are moved, and how hollow viscera, especially those with sphincters, are 

 opened and closed. 



Fig. 1. — A. Elementary voluntary muscular fibres from the leg of a newly-born rabbit after having been exposed to the action 

 of alcohol. Shows well-marked longitudinal and transverse cleavage of the muscle, how the muscle breaks up into sarcous elements 

 or little squares and cubes, and how these may be detached as at a, a', a" (after Bowman). 



B. Sarcous element or cube very greatly enlarged and invested with the double power of vitally changing shape in two 

 directions, namely, horizontally and vertically. The change in shape is effected by combined centripetal and centrifugal movements 

 as indicated by the solid darts {a, h, c, d), and the dotted darts (e,/, g, h). When the sarcous element assumes the shape C (in the 

 horizontal position), it contracts or shortens (see solid darts k, c) in a direction from above downwards, and relaxes or elongates 

 (see dotted darts /, h) laterally. When the sarcous element assumes the shape D, it contracts or shortens laterally (see solid 

 darts b, d), and relaxes or elongates vertically (see dotted darts e, g). The shape of the sarcous elements in the condition of rest 

 is seen at B ; the centrifugal movements are indicated at B, and the centripetal ones at F. 



When two muscles, say a flexor and extensor, are at work, the sarcous elements of the one are shortening, as at 0, while the 

 sarcous elements of the other are elongating, as at 1) (compare with m, n of Fig. 4). The sarcous elements can change shape in 

 two directions (see C and D of Fig. 2). The sarcous elements of both muscles move synchronously and harmoniously to a given 

 end, whether that be the flexion or the extension of a part. The flexor and extensor muscles are not pitted against each other or 



