100 ON THE NATURE AND ACTION OF THE 



then placed upon it, and it beat 24 times in 1 minute. When 

 seized with forceps and placed in cobra-poison it stopped in 

 systole ; but this might be due to the e£fect of the compression 

 by the forceps. 



Experiment LXXI. 



Frog's heart excised. Beats, 30 in the first minute, 34 in the 

 second. 



Cobra-poison applied to it. It immediately stopped, and then 

 began again, but slowly and feebly. Then it beat 26 times per 

 minute, less strongly than before. It gradually recovered and 

 seemed little affected, but stopped about 10 or 15 minutes 

 afterwards. 



Experiment LXXII. 



A cannula was placed in the aorta, and another in the vena 

 cava of a frog. All branches were tied, the heart excised, and 

 placed in connection with H. P. Bowditch's apparatus for 

 keeping a stream of serum circulating through the heart and 

 recording its pulsation by means of a manometer on a revolving 

 cylinder. When fed with pure serum, the heart's contractions 

 were regular and strong ; but whenever serum containing dried 

 cobra-poison in solution (in the proportion of about 2 grains in 

 3 fluid drachms) was introduced into the apparatus the heart 

 stopped almost immediately. As will be seen from the accom- 

 panying tracing, it became partially contracted and gave one or 

 two feeble beats, but did not dilate, and then remained still, the 

 contraction, however, very slowly and gradually increasing. 



Experiment LXXIII. 



A cat was deprived of consciousness by a severe blow on the 

 head ; and a cannula being placed in the trachea, artificial 

 respiration was begun. The thorax was then opened and the 

 heart exposed. A solution of dried cobra-poison in water was 

 then injected into the jugular vein. At first the cardiac pulsa- 

 tions became much quicker, but they were also strong. They 

 next became very small and rapid. Lastly, the right ventricle 

 became much distended, and the heart stopped. The lungs 

 became contracted ; and when force was used to distend them 



