154 ELECTRO-PHYSIOLOGY CHAP. 



ments, and those of Erb (13) on highly- excitable convalescents 

 after severe illnesses (e.g. phthisical subjects and others, in whom 

 a tap on certain skeletal muscles produces a definite swelling, 

 whence little waves of contraction extend to both ends of the 

 muscle-fibres), go to prove that these manifestations are clue not 

 so much to depressed excitability of the muscle as to normal 

 effects of excitation, which Auerbach regards as the direct ex- 

 pression of excessive excitability. Analogous observations of 

 Chwostek (14) and Pick (I.e.) on patients (mostly lean, badly - 

 iiourished individuals) seem, to indicate that the idio-muscular 

 swelling may be regularly provoked in man, if not in all muscles 

 or by every mechanical stimulus. Biceps brachii and the flexor 

 group of the fore-arm seem particularly suited for the purpose. 

 A firm support is, as may be supposed, conducive to the appear- 

 ance of an effect of excitation, and the advantages of it are seen 

 in exciting an appropriate muscle of any animal with uniform 

 excitation before and after supporting it firmly. It is possible 

 that the formation of the swelling in, e.g., the lower limbs of very 

 wasted subjects only, much more rarely on normal, healthy 

 individuals, may depend less upon a definite excitatory state 

 of the muscle than upon the fact that such muscles are 

 more favourable to the action of a mechanical stimulus. It 

 is noticeable that under all conditions when the undulatory 

 contraction appears along with the idio-muscular swelling, the 

 muscle is still capable of twitching, so that the same fibres 

 could transmit rapid, as well as slow, waves of contraction. The 

 same is exhibited, as Klihne showed (I.e. p. 618), in perfectly 

 fresh frog's muscle. Indeed, the manifestation is much more 

 regular there than in the muscles of warm-blooded animals. If 

 the sartorius is hung up by one end, and a cross-section made at 

 the other with scissors, at the same time somewhat stretching the 

 muscle, " so that the play of waves is not lost in retrograde 

 twitches, the little waves will be seen in transmitted light, in 

 which the muscle exhibits beautiful colours, apparently rising in 

 the transparent mass, and subsiding again, so that there is a 

 lively alternation of play of colour in the shimmering muscle." 



Hermann (9, p. 604) made similar observations on the freshly- 

 prepared sartorius, fixed to a cork-plate, and mechanically excited 

 at any point by sticking in a needle, or pressing down a fine 

 wooden chisel. From this point a minute wave or ripple usually 



