POISON APPARATUS 897 



some strain, which pushes it against a shoulder of the maxil- 

 lary bone, and tends to shut off the communication. 



"The injection of the venom, though to all appearance 

 instantaneous, is a complicated process of several rapidly 

 consecutive steps. Forcible voluntary closure of the jaws 

 may always be, if desired, accompanied by a gush of the 

 venom, owing to the arrangement of the muscles which effect 

 such movement of the under jaw. These are the temporals, 

 one of the three of which is situated in such relation to the 

 poison-sac that its swelling in contraction presses upon the 

 receptacle and squeezes out the fluid. The force of ejection 

 is seen when the serpent, striking wildly, misses its aimj 

 under such circumstances, the stream has been seen to spurt 

 five or six feet. A blow given in anger is always accompanied 

 by the spurt of venom, even when the fang fails to engage 

 from whatever cause. But since this result does not follow 

 upon mere closure of the mouth, it is probable that the two 

 posterior temporals ordinarily effect this end, the more 

 powerful action of the anterior temporal (the one which 

 presses upon the poison-sac) being reserved for its special 

 purpose. There is one very curious piece of mechanism to be 

 noted here. Since the serpent always snaps its jaws together 

 in delivering a blow, the points of the erected fangs would 

 penetrate the under jaw itself in case they failed to engage 

 with the object aimed at, were there no contrivance for pre- 

 venting such disaster to the snake. But there is a certain 

 movement among the loose bones of the skull, perhaps not 

 well made out, the result of which is to spread the points of 

 the fangs apart in closure of the mouth, so that they clear 

 the sides of the under jaw, instead of impinging upon it. 



"The complicated mechanism of the act of striking may 

 be thus described: The snake prepares for action by throw- 

 ing itself into a number of superimposed coils, upon the mass 

 of which the neck and a few inches more lie loosely curved, 



