THE RHYTHMIC AND PERISTALTIC MOVEMENTS 101 



Ludwig on the course of the nerve fibres running through the 

 auricles in the case of the frog, and have been called Ludwig's 

 ganglia, and others in the course of the nerve fibres to the ventricle 

 at the auriculo-ventricular junction which have been called Bidder's 

 ganglia. < 



These accessory groups of nerve cells do not initiate rhythmic 

 impulses as long as the sinus ganglia are intact ; if, however, 

 the latter are removed, then these cells are capable of discharging 

 rhythmic impulses in a similar manner to those of the sinus 

 ganglia. The conceptions may be represented as follows : 



Sinua Auricular Ventricular 



musculature musculature musculature 



nerve path to ^-K nerve path to 



Remak's Ludn>ig'3 Bidder's 



centre centre centre 



The rhythmic discharges from the motor centre in the sinus 

 along the nerve fibres necessarily cause the sinus muscle to con- 

 tract first, because they pass direct to that muscle ; they cause 

 the auricle to contract next, because of the delay of the impulse 

 caused by the passage through Ludwig's centre, and finally the 

 ventricle contracts last, owing to the further delay caused by the 

 passage through Bidder's centre. If the sinus be removed then 

 Ludwig's centre will become the motor centre, and still the ven- 

 tricle will respond in due sequence to the auricle because still 

 the impulse has to pass through Bidder's centre to get to the 

 ventricle. 



This view represents the neurogenic theory of the heart beat 

 as it was developed in the first instance ; it allows no rhythmic 

 power in the cardiac muscle itself, which contracts simply to each 

 rhythmic nervous discharge, just as though it were a piece of 

 the muscle of the diaphragm responding to the discharges from 

 the respiratory centre. 



There is however abundant proof that all muscular tissue 

 possesses to a greater or less degree the power of rhythmic 

 response to an appropriate constant stimulus whether such stim- 

 ulus be of a physical or chemical nature. Thus even ordinary 

 striated muscle can be made to contract rhythmically by im- 

 mersion in a suitable solution, and Mines gives instances of 



