234 CIRCULATION. 



ago on alligators, we noticed a singular peculiarity which 

 throws some light on the question we are now considering. 

 Desiring to demonstrate to the class at the New Orleans 

 School of Medicine the action of the heart in this animal, an 

 alligator six feet in length was poisoned with woorara, and 

 the heart exposed. The animal came under the influence of 

 the poison in about thirty minutes, when the dissection was 

 commenced, and was quite dead when the heart was exposed. 

 The pneumogastrics were then exposed and galvanized, with 

 the effect of promptly arresting the action of the heart. This 

 observation was verified in another experiment. We were 

 at first at a loss to account for the absence of effect of the 

 woorara on the motor filaments of the pneumogastric nerves ; 

 but on reflection thought it might be due to slow absorption of 

 the poison in so large a cold-blooded animal. With a view 

 of ascertaining whether there is any difference in the prompt- 

 ness with which different nerves in the body are affected by 

 this agent, we made the following experiment upon a dog. 

 The animal was brought under the influence of ether, and 

 the heart, the pneumogastrics, and the sciatic nerve were 

 exposed. Galvanization of the sciatic produced muscular 

 contraction, and of the pneumogastrics arrested the heart 

 promptly. A grain of woorara, dissolved in water, was then 

 injected under the skin of the thigh. One hour after the 

 injection of the woorara, the sciatic was found insensible to 

 galvanism, but the heart could be arrested by galvanization 

 of the pneumogastrics, though it required a powerful current. 

 A weaker current diminished the frequency, and increased 

 the force, of its pulsations. 1 In this experiment, the opera- 

 tion of opening the chest undoubtedly diminished the activity 

 of absorption of the poison, and consequently retarded its ef- 

 fects upon the nervous system. Taken in connection with 



1 This increase in the force of the heart, which accompanied the diminution in 

 the frequency of its pulsations, consequent upon feeble galvanization of the pneu- 

 mogastrics, was constantly observed in many experiments. The force of the pul- 

 sations was measured by the cardiometer. 



