Snakes and Frogs and Their Relatives [ 201 



depend on the species. Usually they are elliptical, with flattened 

 ends.. When first laid, the eggs are covered with a moist and sticky 

 skin which gradually becomes tough and leathery. They absorb 

 water and thus continue to grow after leaving the mother's body 

 until they have increased about one-third in size. 



THE EGG-TOOTH 



Projecting from the middle of the upper jaw of the full- 

 grown embryo is an egg-tooth with which it slits the tough egg 

 skin when it is ready to emerge as a perfectly formed young snake. 

 If you rub your finger over the nose of a baby snake you may feel 

 this egg-tooth, which remains until the baby is about a week old. 



How Snakes Kill 



It may well be that the horror snakes arouse in many people 

 is evoked by their methods of killing. A tiger's prey is just as dead 

 as a snake's victim; but constriction and poison somehow seem 

 more sinister means of inflicting death than fang and claw. 



Snakes get their food in three different ways. For the first and 

 most primitive, the reptile seizes its prey by throwing its coils 

 about a victim without constriction and then swallows it alive. 

 Constriction is a second method, suffocating the victim until its 

 heart and lungs can no longer function properly. At one time it 

 was believed that constrictors crushed the bones of any creature 

 within their grip; today we know this theory to be erroneous. 



Poison is the third method of killing. There are several types 

 of poisonous snakes; those known as vipers and pit vipers have 

 the most effective poison apparatus. The group includes rattle- 

 snakes, copperheads, water moccasins, bushmasters, and the trop- 

 ical fer-de-lance. 



How POISON FANGS WORK 



All these snakes have hollow fangs in the upper jaw, 

 firmly anchored to the bone above, which they can move to 

 thrust the fangs forward for a strike. When they are not in use, 

 the fangs can be folded back against the roof of the mouth. 



As a child, you may have been told that the mere pressure of a 

 snake's fangs against a solid substance brought forth the venom. 



