OP THE VENOM OF THE RATTLESNAKE. 55 



selves naturally and conveniently into two classes, which I shall term acute and 

 chronic, or primary and secondary poisoning. 



While in the batrachia the distinction between these two sets of cases is sufScicntly 

 clear, it is less well marked than in warm-blooded animals. At the time I was 

 engaged upon this portion of my investigation, the active serpents in my collection 

 were not so large as those which I afterwards received. This may account for the 

 fact that, although I have some records of frogs more or less acutely poisoned, the 

 majority of those bitten lived long enough to exhibit, in a marked manner, the 

 secondary lesions which I shall have occasion hereafter to describe. 



The class of cases which I shall term acute, were marked by the negative cha- 

 racter of the symptoms. In them the local signs of poisoning were very slight, 

 and the changes in the blood which occurred where life was prolonged after a 

 serious bite, were absent, or but very slightly marked. 



Experiment. — A large frog recently caught, was attached to a string and lowered 

 into a cage containing four snakes, none of which were over thirty-six inches 

 long. As I had often observed, no provocation induced them to strike the frog, and, 

 therefore, after many vain efibrts, I drew a snake into the snake-tube, and placed the 

 frog in its jaws. The serpent bit with eagerness, and the frog, uttering a cry, leaped 

 from its re-opened jaws to the floor, and for a few moments used its legs so well as 

 to avoid being caught. When at length it was secured, I searched in vain for the 

 fang wound, which must have been very small ; I did not discover it until after 

 death, although I was sure that the skin had been penetrated, because a large 

 bubble of air had found entry to the dorsal sub-cuticular sac. 



The presence of air in this situation often enabled me to be confident that the 

 fang had pierced the skin. It is occasioned by the attempt on the part of the serpent 

 to withdraw its fang, which, catching, raises the loose skin, and creating a partial 

 vacuum, thus draws air alongside of the fang into the subjacent cavities. A little 

 quivering on the right flank, also, caused me to suspect that as the part bitten. 

 Except in dogs, who shiver so much from mere fright, the local muscular twitchings 

 alluded to are also of some value in calling attention to the part bitten. Two hours 

 after this frog was poisoned, it was dead, having exhibited during the interval occa- 

 sional convulsive motions of the limbs. 



P. M. Dissection. — As soon as all motions, reflex and other, were at an end, the 

 thorax and belly were laid open. The intestines responded to irritants. The heart 

 was beating feebly, but in all of its cavities, and was large and dark. It ceased to 

 pulsate at the close of three hours and ten minutes after the poisoning, and on being 

 opened, was found to contain blood which coagulated perfectly after short exposure. 

 The clot was well formed and firm. The muscles were irritable to all forms of 

 stimulus during eleven hours, and, as I have usually observed, this property lasted 

 longest in the muscles under the cliin.^ Nervous irritability existed until the close 

 of the fourth hour. The seat of the wound was the right flank, into the muscles 



* Brown-Sequard, Bernard, Vulpian, and before them, Fontana, Lave noted the long retention of irri- 

 tability by the diaphragm muscles. In the frog, the sub-mental group corresponds in function to these, 

 as I have shown elsewhere. 



