700 
PROFESSOR HARLEY ON THE INFLUENCE OF 
Secretary to the Zoological Gardens, the loan of two African Puff Adders. They were 
3 feet in length, and about 8 inches in circumference at the thickest part. 
The physiological action of animal poisons being as yet imperfectly understood, before 
alluding to the special action of the poison on the blood, I shall briefly relate the history 
of one of the experiments. 
The experiments were performed at University College, in the presence of my col- 
leagues, Professors Sharpey, Ellis, and Williamson. The serpents had eaten nothing 
during eight days, so it was supposed that their poison-bags were well charged with 
venom. 
A large dog was bitten by one of the snakes over the right eye. The immediate 
appearance of a drop of blood indicated the position of the wound. In three minutes 
the dog became very restless, and gave a low whine as if in pain. After moving about 
the room for ten minutes searching for a comfortable place to lie down on, he placed 
himself in the coolest part of the chamber, and laid his head on the cold stones, as if to 
relieve headache. He moaned as if in distress. In a quarter of an hour after he 
received his wound the pulse had fallen from 100 to 64 per minute. As the effects of 
the poison passed away the pulse gradually recovered, and in twenty-five minutes it was 
again as high as 96 per minute. 
In one hour after being bitten the dog had so far got over the effects of the poison 
as to be able to run about. 
The serpent was once more allowed to bite him. The same train of symptoms again 
appeared, but in a more intense degree, and within twenty-five minutes he had become 
insensible. He looked as if in a profound sleep, from which he could not be roused. 
The respirations were 40 per minute, and the pulse so feeble in the femoral artery that 
it was found impossible to count it. The pupils were dilated. 
Half an hour after being bitten the second time convulsive twitchings began to appear 
in the fore limbs and in the muscles of the neck. In ten minutes more the whole body 
became convulsed. The limbs were stretched out, and the head jerked backwards. 
During the convulsions the respirations rose to 90 per minute ; but they subsided to 40 
in the intervals. The temperature of the rectum gradually fell in the course of one 
hour and a half from 38° to 35° C. In two hours the respirations were reduced to 9 per 
minute, the animal temperature at the same time being 34° C. The pulse was com- 
pletely imperceptible ; even the heart’s action could not be felt through the ribs. 
In two hours and a quarter the animal appeared to be dead; but on making an 
incision into the thorax he gave a gasp. After waiting some time, without observing 
any further sign of life, another incision was made, when he again gasped, but only 
once. On opening the thorax the heart was found pulsating at the rate of 60 per 
minute ; it was, however, more like a quivering than a true pulsation. The tissues of 
this and of the other animals killed by the puff adders presented a very strange appear- 
ance, namely, numerous extravasations of blood throughout the body, some small, some 
large. For example, in this animal there was an extravasation of blood into the ante- 
