K) rilY.-KM.txiY OF MUSCLES AND M'KYKS. 



IP it al way- 1 lie .-ill i ic ill the ruse i >f different muscles. Ou 



comparing thick with thin muscles, il appears, in the first 



J)l: ice. thill (he extension in the case of thick muscles he- 

 ciii ncs less in |)ni]nirt Ion as the Weighl :i]i|lic(l increases ; 

 ;ind that tlie decrease in the height of elevation corre- 

 -pondingto the iiicrea-e in the weight applied proceeds 

 less rapidly ; so t hat much greater weights can be raised 

 by thick than hy thin muscles. On the other hand, it 

 appears that in the case of muscles of eipial thickness 

 the height of elevation is greater in proportion as 

 the muscle-fibres are longer. I'nder an equal weight 

 the height of elexation increase's proportionately with 

 the length of the in iisde-fil ires. They decrease with 

 increased weight; and they do this more rapidly in the 

 case of thin than of thick muscles. 



4. In calculating the amount of work accomplished 

 liy a mii-cle, only the raising of the weight is taken into 

 consideration. When, however, the ordinary method 

 of irritating the muscle is applied, the weight which 

 is raised sinks hack after each pulsation to its former 

 height. The muscular work accomplished at each pul- 

 sation is, therefore, cancelled. It [s probably converted 

 into warmth. It is, however, possible, to retain the 

 \\eii_dit at the height to which il was raised by t he muscle. 

 A. Kick accomplished this very ingeniously liy can-ing 

 t he muscle to act on a light Lever, which moves a wheel 



each time it rises, but leases the same wh-el undis- 

 turbed when it again .-inks. A thread, on which the 

 \\eight han^.-, p iver the axis of the wheel. The 



etlect of t his arrangement is that the muscle at each 

 pulsation turns the \\hed slightly, and lhu> slowly 

 rai-es the \\ejnht. If the muscle is made to pulsate 

 frequently, the weighi is rai-ed somewhat higher each 



