100 HIYSIOLOGY OF Ml'SCLES AND NERVES. 



and this, rise can be indicated on a rapidly-moving 



mvograph plate. If two of these small levers are 

 placed near the ends of a long muscle, and one of the 

 ends is then irritated, the nearer lever is first raised, 

 the more remote not till later. This litter, aee may be 

 read off the plate of the myograph, and thus the 

 >|tecd of the propagation from one lever to the other 

 may be calculated. Aeby, who first tried this experi- 

 ment, found that the speed was from one to two metres 

 in the second, or, in other words, that a contraction 

 excited at one point of a muscle-fibre requires a period 

 of from about TT^ to -fo of a second to advance one 

 centimetre. More recent measurements by Bernstein 

 and Hermann show the higher value of from three to four 

 metres in the second, ^n the death of the muscle, 

 t he rate of propagat ion becomes r ,,nt inually less, finally 

 ceasing entirely in muscles which are just about to pa 

 into a state of death-si iff ue->. so that on irritation only 

 a slight thickening is seen at the point directly irritated, 

 and this does not propagate it.-elf. Under all circum- 

 stances, however, the excited contraction is confined to 

 the fibres which are themselves actually irritated, the 

 neighbouring fibres remaining perfectly quiescent. In 

 smooth miiscle-Jibres, however, it is found that tin- 

 contractions excited at one p"int propagate themseho 

 in (he adjacent fibres also. The marked distinction 

 which thus appears to exist between smooth and striated 

 nm-cles \\ould, it is true, di-appear if the views of 

 Kngelmann, resulting frm his >t udy of the urinary 

 dift, are continued. According to that writer, the 

 mu-cular ma-s of the urinary duct does not COnsisj 

 during life of separate mu-de-libre cells, but forms 

 a homogeneous connected mass \\hidi only separate- 



