OF THE CALABAR BEAN, 749 



gate the possible influences of the cerebro-spinal nervous system, whether exerted 

 through the vagi or through the spinal nerves, and the possible influences of the 

 sympathetic system, whether exerted through the great sympathetic trunks and 

 their branches or through the ganglia contained in the heart's substance. Any 

 effect on idio-muscular contractility has been already abundantly disproved ; but 

 it will be necessary to observe how far the impairment and cessation of respira- 

 tion may explain the cardiac effects in warm-blooded animals. 



The paralysis of the heart in diastole and the diminution in the frequency of its 

 contractions by protracted periods of rest in a dilated condition, as well as the fre- 

 quent renewal of its action after a long pause in diastole, might, in the first place, 

 suggest that the inhibitory function of the vagi nerves was being exerted . On this 

 account, it may be advisable to examine their condition during Calabar bean 



poisoning. 



Experiment LI. 

 An active frog was selected, of the weight of 863 grains, and its heart and two vagi nerves 

 were exposed. The latter were separately tested by galvanism, and each produced stoppage 

 of the heart's action, in diastole. A few minutes afterwards, the average of the heart's con- 

 tractions was ascertained to be fifty-eight in the minute. Three grains of extract, in a few 

 drops of water, were injected into the subcutaneous tissue of the two thighs — one-half into each. 

 2 minutes afterwards, cardiac contractions = 54 per min. 

 4 =47 



6 „ 40 „ 



8 „ „ = 37 „ 



= 36 

 galvanism of the left vagus produced stoppage in diastole, 

 cardiac contractions = 34 per min. 



„ = 33 „ Contractions feeble. 



f Heart dark in systole, as well as in 

 " \ diastole. 

 = 24 

 = 20 

 — 19 

 galvanism of the left vagus produced stoppage for one minute, 

 cardiac contractions = 15 per min. 



„ = 18 „ 



_ -J a ( Marked pause between auricular 



\ and ventricular contractions. 

 = 12 

 galvanism of the left vagus produced stoppage of all the chambers, 

 cardiac contractions were irregular, on being renewed; only twelve 



ventricular now occurring to eighteen auricular, per minute, 

 cardiac contractions continue, with the above irregularity, 

 cardiac contractions still irregular ; galvanism of the left vagus produced 

 30 ,, stoppage of all the chambers, but a stronger current was required 



than before. 

 galvanism of either sciatic nerve caused movements confined to the 

 limb whose nerve was stimulated. 

 1 „ 40 ,, cardiac contractions continue irregular, as above. 



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