64 PHYSIOLOGY AND TOXICOLOGY 



CHAPTER VI. 



TOXICOLOGICAL ACTIOX OF THE VEXOM UPON WARM-BLOODED 



ANIMALS. 



We shall now enter, without other comment, on the study of the effects of Cro- 

 talus venom upon warm-blooded animals. 



Of all warm-blooded creatures, birds are most susceptible to the influence of this 

 poison. So sudden, indeed, were its effects in some of them, that when the dose of the 

 venom was large, there was hardly time to observe the resultant phenomena. In 

 larger birds this extreme sensibility to the poison also existed, when the dose was in 

 pi'oportion greater. So minute, however, was the quantity required to kill a small 

 bird, such as the reed-bird, that under certain circumstances these little creatures 

 became very delicate tests of the presence or relative activity of the venom. 



Experiment. — A pigeon was lowered into the snake-box, and was struck once, high 

 up on the back, by a snake of middle size, which had just used its fangs. Upon this 

 occasion, both fangs were buried deeply. On being released, the pigeon walked 

 across the table, and seeking a corner, remained at rest, until, at the close of three 

 minutes it fell down, and immediately began to breathe convulsively, now and then 

 gaping, and making efforts to rise. The difficulty in the respiration seemed to be 

 due to the general weakness, which interfered with all the other movements at the 

 same time. The bird became more and more feeble, the breathing more labored, 

 and at the end of the seventh minute the head fell to one side, the breathing 

 ceased, and the bird died without convulsions. 



P. M. Section. — Both fang marks were surrounded, by circles of extravasated 

 blood, about three lines in breadth. The motor nerves of the wings and legs were 

 irritable nine minutes after death. The muscles remained irritable during twenty- 

 nine minutes, when post-mortem rigor appeared in the legs, and soon became general. 

 The heart beat with all its cavities, four minutes after respiration ceased. Both 

 auricles and ventricles were sensitive to mechanical stimulus nine minutes after 

 death. Two minutes later, the ventricles ceased to respond, but the auricles were 

 more or less irritable fifteen minutes after death. The blood coagulated moderately 

 well. It was very dark, but on exposure became bright red. 



Ex]}eriment. — Temperature 74° F. A pigeon secured by a string was thrown into 

 a snake-box. Two snakes of middle size, two and a half to three feet long, struck 

 at it as soon as it began to flutter. The pigeon was at once removed and put on 

 the table, where, in two minutes it showed signs of weakness, staggered to and fro, 

 and at last, as usual, sought refuge in a corner. At the si.xth minute, its breath- 

 ing became labored and jerking, and the muscles about the wound wei'e twitching 



