But the distinguishing feature of venomous serpents is their poison fangs and glands, by which the fatal fluid is secreted. They kill by a stroke, or blow, which drives the fang into the flesh, and there discharges the venom. Some are intensely active and fierce, and will spring upon the traveler, as the fer de lance and the haje. Others, as the northern rattlesnake, seldom attack but rather retreat from man.
The fangs are in the upper jaw, as shown in Fig. 4. In a rattle-snake, four feet in length, they are about half an inch long. Behind them are the glands, which secrete the poisonous fluid, from five to ten drops of which have, in some cases, been obtained from a single fang. It is tasteless, and nearly colorless, and, on being dried up, leaves minute crystalline spicules, or scales. The venom of all the poisonous species of serpents appears to be essentially the same, but differs in intensity or virulence. The fang is perforated by a small canal in
Fig. 13.
The Horned Puff-Adder.
front of the usual pulp-cavity, through which the venom is discharged by pressure brought to bear upon the glands from the act of striking. A rattlesnake confined in a cage, when irritated, struck against the wire bars with its fangs, throwing the venom a distance of three feet. The fang usually lies flat, and partly hidden in the fleshy tissue, but is erected when needed for use; and it is only when erected that its connection with the venom-gland is so adjusted that the fluid may be thrown out.
The poison is always more or less dangerous to animal life. Cattle have died from a bite of the fer de lance in a few hours. Smaller animals die directly. Horses have been killed by rattlesnakes, and people bitten by them may die in a few minutes or in a few days, but
