104 ACTION OF FLUIDS ON THE HEART. 



of atropine and muscarin have a similar action (v. Basch). These experiments 

 show that, provided no nervous apparatus exists within the heart-apex, the cause of 

 the varying contraction is to be sought for in the musculature of the heart 

 (Kronecker), and that the stimulus necessary for the systole of the heart's- 

 apex may arise within itself (Aubert). If there is no nervous apparatus of any 

 kind present, then we must assume that the heart-muscle may execute rhythmical 

 movements independently of the presence of any nervous mechanism, although it 

 is usually assumed that the ganglia excite the heart-muscle to pulsate rhythmically. 

 It is by no means definitely proved that the heart-apex is devoid of all nervous 

 structures, which may act as originators of these rhythmical impulses. 



The "Heart" preparation in many respects behaves like the foregoing, i.e., 

 it is exhausted after a time by the continued application of normal saline 

 solution (0*6 per cent. NaCl), while its activity may be restored by supplying it 

 with albuminous and other fluids (p. 99).] 



[(5.) Luciani found that such a heart, when filled with pure serum, 

 produced groups of pulsations with a long diastolic pause between every 

 two groups (Fig. 34). The successive beats in each group assume a 

 " staircase" character (p. 107). These periodic groups undergo many 



Fig. 34. 



Four groups of pulsations with intervening pauses, as obtained by Luciani, with 

 their "staircase" character. The points on the abscissa were marked every 

 ten seconds. 



changes ; they occur when the heart is filled with pure serum free 

 from blood-corpuscles, and they disappear and give place to regular 

 pulsations when defibrinated blood or serum containing haemoglobin 

 or normal saline solution (Rossbach) is used. They also occur when 

 the blood within the heart has become dark-coloured i.e., when it 

 has been deprived of certain of its constituents and if a trace of 

 veratrin be added to bright-red blood they occur.] 



(6.) The same apparatus permits of the application of electrical stimuli 

 to either of the above-named preparations. An apex-preparation, when 

 stimulated with even a weak induction shock, always gives its maximal 

 contraction, and when a tetanising current is applied tetanus does not 

 occur (Kronecker and Stirling). When the opening and closing 

 shocks of a sufficiently strong constant current are applied to the 

 heart-apex, it contracts with each closing or opening shock. [When 

 a constant current is applied to the lower two-thirds of the ventricle 

 (heart-apex), under certain conditions the apex contracts rhythmically. 



