NOTES AND ADDITIONS. 



315 



A special form of secondary pulsation effected through the 

 nerve has been described bydu Bois-Reymondas paradoxical 

 pulsation. If a constant current is passed through the branch 

 of the sciatic nerve to which allusion is made in Note 4, 

 which passes to the flexor muscle of the lower leg, then the 

 calf-muscle may also pulsate when the current is closed and 



FIG. 75. SECONDARY PULSATION EFFECTED BY NERVE. 



opened. This is an apparent exception to the law of the 

 isolated transmission of the excitement (cf. p. 117); but 

 actually the excitement has not passed from the irritated 

 fibres to the adjacent fibres, but the electrotonic current of 

 the one fibre has flowed through the neighbouring fibres and 

 lias independently irritated them. 



14. PARELECTRONOMY (p. 237). 



The real causes of parelectronomy and the conditions 

 tinder which it is more or less strongly developed, are as yet 



