CHANGE OF FORM IN MUSCLE DURING ACTIVITY 153 



swellings which exactly resembled those on the muscles of the 

 decapitated subject (a mode of demonstration to which Kiihne 

 subsequently referred as " familiar to every gymnast "), L. Auer- 

 bach followed up these effects more thoroughly, and communicated 

 his observations in an essay, " Ueber topische Muskelreizung/' 

 published in the Jahresberichten d. ScklcssiseJien Gesellschaft, 

 1861 (Nat. Wiss. t Mecl AUheilg., Heft 3). He produced local 

 excitation by blows with a percussion hammer, and reported that 

 very generally in man, and in many muscles of the body, an 

 almost conical lump rises up on the spot thus percussed, lasting 

 as a rule 3-5 sees, with comparatively no alteration, and then 

 sinking slowly down again at the same point of the muscle. He 

 refers some minor apparently local changes of the lump to the 

 collective shortening of the muscle-bundle from the mechanical 

 excitation. In many " rare " cases (Auerbach quotes four such 

 individuals) there is, moreover, an undulatory manifestation, but 

 he was only able to induce it in pectoralis major and the inner 

 half of biceps by smart taps on a spot overlying the bone. This 

 wave-like appearance consists of a low crest rising up on either 

 side of the idio-muscular swelling, which gradually spreads like a 

 wave on the surface of smooth water, at very moderate velocity, 

 towards the two ends of the muscle. He never observed a back- 

 ward motion of these waves in the human subject. On the 

 other hand, it was very conspicuous in the rabbit, where he was 

 able to provoke Scruff's play of waves on most muscles by gentle 

 mechanical stimulation, <?//. tapping, or stroking vertically with a 

 blunt object. According to A. Pick, the most favourable muscles 

 are the ventral section of pectoralis major, and the sterno-mastoid. 

 On stroking these muscles vigorously with the handle of a scalpel 

 across the direction of the fibres, a linear swelling appears at the 

 excited point, after a brief twitch of the muscle-bundle, while a flat, 

 slowly-transmitted wave spreads towards the intersection of the 

 muscle in one or both directions from the seat of excitation. After 

 death this undulatory contraction always disappears before the 

 idio-muscular swelling, which can still be provoked several hours 

 later. Sometimes the swelling seems to bifurcate by the formation 

 of a hollow at the point excited, while a wave spreads out on 

 both sides towards either end of the muscle, and may eventually 

 be reflected back again. The same has been observed in the 

 living human subject by Baierlacher (12). Both these experi- 



