The fang is folded back ‘with an action comparable to the shutting of the blade of a pocket-knife; ... one set of muscles prepares the fangs for action, the other set stows them away when not wanted.... The fangs are further protected by a contrivance for sheathing them, like a sword in its scabbard. A fold of mucous membrane envelops the tooth like a hood.... The erection causes the sheath to slip, like the finger of a glove, and gather in folds round its base.... It can be examined without dissection.’ (And with the naked eye in a large viper, even during life, you may sometimes perceive this sheath or hood half off.) ‘Each developing fang is enclosed in a separate capsule,’ says Dr. Mitchel, which is just what I thought I saw in ‘grovelling’ up the poor Bushmaster’s reserve fangs. There was an immense deal of loose skin to remove, which under skilful manipulation would doubtless have presented the form of sheaths of various sizes. At last I came to a great deep cavity as big as a bean or a hazel nut, and this I left neat and uninjured for some one else to explore. It might have been the poison gland! The young Jararaca’s mouth is too small to reveal its mysteries. But now we come to the most amazing of all the wondrous detail of this living hypodermic syringe. Those who have seen a viper or a rattlesnake strike its prey, are cognisant of the lightning-like rapidity of the action. So swift is it that often a spectator is not sure whether the snake touched the victim or not. A flicker, a flash, and the bite has been given. Dr. Mitchel, describing the singular inactivity of rattlesnakes in confinement, points out the striking contrast between this repose and the perilous rapidity of their stroke. Now let us look at the amount of business transacted in that flash of time. Says Dr. Elliot Coues: ‘The train of action is first reaching the object; secondly, the blow; thirdly, the penetration; fourthly, the injection; and fifthly, the enlargement of the wound (the latter by dragging upon it the whole weight of the body by the contraction of certain muscles, which cause the fangs to be buried deeper and thus enlarge the puncture); and all these five actions accomplished in that instantaneous stroke!’ This is what Fayrer means when explaining that ‘the real bite is when the snake seizes, retains its hold, and thoroughly imbeds its fangs.’ ‘Sometimes the lower teeth and the palatine become entangled (and sometimes a fang is left in the wound).... The force of ejection may be seen when a serpent striking violently misses its aim, and the stream has been seen to spirt five or six feet. A blow given in anger is always accompanied by the spirt of venom, even if the fangs fail to engage.’ ... Another curious piece of mechanism, and one not previously described that I am aware of, is a provision for the fangs when they fail to bite. ‘A serpent always snaps his jaws together, and thoroughly _closes them_ when he strikes;