OF THE CALABAR BEAN. 751 



Experiment LIII. 

 The heart and the two vagi nerves were exposed and the latter divided in a frog, weighing 

 700 grains, and, a few minutes later, the cardiac contractions were found to have an average of 

 sixty-six in the minute. Two grains of extract, in ten minims of distilled water, were then 

 injected into each thigh (altogether four grains). 



2 minutes afterwards, cardiac contractions = 60 per miu. 



4 „ „ = 60 ., 



6 ., = 53 



8 „ „ =46 ,. 



10 ., „ =39 ,. 



12 ., „ = 31 ., 



14 ., ., =27 ., 



16 ., „ =24 ., 



18 „ „ =22 „ 



20 ., „ =18 „ 



22 „ „ =16 



24 ., „ =13 



26 ., „ = 14 



28 „ „ = 12 



( All the chambers are of dark 

 ( colour, even in systole. 



f Ventricular contraction is 

 \. extremely feeble. 



30 ., „ =10 ., 



35 ., „ =9 „ 



40 „ „ irregular ; six ventricular for twelve auricular. 



42 ,, ,, stopped in diastole, for thirty- five seconds. 



The heart then resumed its previous unrhythmical action of six ventricular to twelve auri- 

 cular movements in the minute, and continued to contract, with various changes of irregularity, 

 for many hours longer. 



It would needlessly occupy space, were I to narrate any other of the many expe- 

 riments that were performed with frogs whose vagi had been divided ; as the results, 

 and even the details, were in all of them very much the same. It might be proper 

 to instance, at this place, an experiment of the same character on a warm-blooded 

 animal, but I content myself by referring to Experiment LXL, at page 763. 



In curare we possess an agent that, within a few minutes after its exhibition. 



produces complete paralysis of all the motor nerves, including the vagi.* It will. 



therefore, act as effectually as division, in preventing any inhibitory influence being 



exerted on the heart. 



Experiment LTV. 



A small dose of curare was inserted under the skin of a frog's back. Ten minutes after- 

 wards, the animal was perfectly paralysed. At twenty minutes, its heart was exposed, and 

 observed to be contracting fifty-four times in the minute. The vagi and sciatic nerves were 

 tested by galvanism, and their conductivity was found to be completely destroyed. Three 

 grains of extract of physostigma, in water, were injected into the two thighs. The usual cardiac 

 effects were produced within the time that might have been expected, from such a dose ; irregu- 

 larity of the rhythm having occurred in forty-four minutes, and final paralysis, with all the 

 chambers dark, full and dilated, in a few minutes later. 



* Claude Bernard, Lecons sur les effects des Subs. Tox. &c, p. 352 ; Kolt.tker, he. cit. ; 

 Martin- Magron, Journal de la Physiologie, 1859, p. 649. &c. 



VOL. XXIV. PAET TIL 9 S 



