1882.] in the function of the cardiac muscle. 281 



of contractions, for, when the strip has once been brought into 

 this condition of spontaneous rhythm, it will continue beating 

 for very many hours. Thus I have induced spontaneous rhythm 

 in this way and have found the piece still contracting rhythmically 

 and well 30 hours after suspension, i.e. between 28 and 29 hours 

 after the commencement of the rhythm. 



Also the control piece which is left entirely to itself will after 

 a time begin to contract rhythmically so that the power of rhyth- 

 mical contraction exists in both strips ; the effect therefore of 

 the previous stimulation is not to invest the tissue with a, property 

 which it did not possess before, but to quicken the establishment,, 

 of certain conditions in the muscular substance upon which the 

 manifestation of that property depends. As far as I have yet 

 seen the beneficial effects of previous stimulation are sufficient 

 to shorten the time by one-half; the strip which is left to itself 

 does not begin to beat until nearly four hours after suspension, 

 whereas the stimulated piece beats between one and two hours ; 

 in addition the contractions of the latter are more vigorous, the 

 rhythm is more regular and quicker. 



Here again, then, experiment points to a difference of degree 

 rather than of kind between the rhythm of the whole ventricle 

 and that of the isolated strip from the apex. In each case the 

 rhythmical contractions take time to be manifested, the difference 

 being in the length of time ; in each case the rhythm is at first 

 slow and gradually quickens up to a definite rate and in each 

 case the rhythm when once established is practically permanent. 

 The duration of the preliminary standstill may be most markedly 

 shortened by sending a weak interrupted current and single in- 

 duction shocks through the apex strip ; while in the whole 

 ventricle it may be removed altogether by sending a supply of 

 blood through the coronary system. In the apex the previous 

 stimulation causes the resulting spontaneous rhythm to be more 

 regular and quicker ; in the whole ventricle the rate of the spon- 

 taneous rhythm depends directly upon the pressure in the coronary 

 blood-vessels. 



Further, this rhythm is clearly due to the muscle itself, for 

 ganglion cells are not to be found in this strip, no foreign blood 

 is used as in the ordinary method of obtaining rhythmical apex 

 contractions, and the mechanical stimulus of the stretching of the 

 tissue in consequence of the method used is not sufficient to 

 explain the phenomenon in question, for, as soon as the rhythm 

 is well established, the strip can be removed, laid down and kept 

 moist, and will still continue to boat rhythmically in this position 

 for hours; nay more, it can be cut into pieces and each piece 

 will beat just as though, according to the accepted theory, it were 

 provided with ganglia. In the same way a strip of the muscular 



