CONTRACTION BY WATER. 451 



before. But, even setting disturbances of temperature aside, such ex- 

 periments are of no kind of value, since they contain no provision for the 

 removal of the wasted material of the muscle, which still continues a part 

 thereof, though it has become, to all intents and purposes, extraneous, 

 and would, if in the living system, have been instantly removed by the 

 veins. 



And now, by the aid of these doctrines, we may comprehend the full 

 significance of those conditions, which have been long known 

 to physiologists, which have cast such a mystery over muscu- of partial hy- 

 lar contraction, and led to such a diversity of views as re- P theses - + 

 spects its true explanation. We see that they were right who asserted 

 that muscular contraction is a function of nutrition, though they were 

 wrong in saying that it is therefore of a vital, and consequently of an 

 inexplicable nature. They, too, were right who asserted that muscular 

 contraction depends on respiration, and that the higher the rate of that 

 function the more energetic the muscular power will be. They, too, were 

 right who asserted that muscular contraction is manifested by a waste 

 of tissue, and that that waste may be measured, if certain corrections are 

 applied, by the quantity of urea and sulphuric acid in the urine. They, 

 too, were right who asserted that there is a connection between the co- 

 agulability of the blood and the energy of muscular contraction in the 

 various tribes of life, for the speed of repair depends on the percentage 

 of fibrin in the blood, and so, too, does the speed of coagulation. They, 

 too, were right who asserted the connection between muscular contrac- 

 tion and the speed or slowness of the circulation of the blood. All these, 

 and many other partial hypotheses, are the necessary consequences of the 

 more general doctrine, that muscular contraction is the result of loss of 

 muscular substance. 



There remains a phenomenon to which our attention has to be direct- 

 ed in the conclusion of this subject. It is the contractions _ t 



. . . -,-, nil- -i. r Contraction 



which may be observed under the microscope when a lascicu- produced by 

 lus is submitted to water. These contractions commence in water ' 

 isolated places, from which they spread in all directions, and so move 

 about from end to end, often interfering with one another, the fasciculus 

 thickening where the contraction is greatest, and eventually the whole 

 length becoming involved. The ultimate degree of contraction that can 

 be reached reduces the fasciculus to one third of its original length. With 

 this contraction, through the agency of water or other such liquids, we 

 may connect those contractions which ensue under the pressure or dis- 

 turbance of some hard body, as by the touch of a pin. 



From these cases it might be supposed that muscular contractility can 

 take place independently of chemical destruction, but a more critical ex- 

 amination of them will satisfy us that they ensue as the natural conse- 



