HOW THEIR. YOUNG ARE BORN. 221 
THE HIss OF THE PUFF ADDER. 
It can hiss loudly, and many a man has cause to be grateful 
that Nature has provided the Puff Adder with that mode of warn- 
ing his enemies.. 
The Puff Adder hisses by drawing air into its sac-like lung 
and forcing it out rapidly through the glottis and nostrils. These 
and most other snakes have only one active lung, which is in the 
form of a long bag. The second lung is rudimentary. 
THE FANGS. 
The dentition of the Puff Adder is elaborate. The poison 
fangs are long and powerful. They are hollow, not grooved 
like those of the Cobra family. Naturally, if such large 
fangs were fixed solidly in the jaw like those of the Cobra, the 
snake could not close its mouth. Nature has provided against 
this, and furnished it with fangs with hinges. The fangs are 
set in the anterior maxillary bone, which can be moved backwards 
and forwards like a hinge . So, when the mouth closes, the fangs 
lie along the sides of the upper jaw, enveloped in a protecting 
sheath, known as the mucous capsule or vagina dentis. The 
small teeth in the back part of the upper jaw, and in the lower 
jaw, are for the purpose of helping to hold the captured prey, and 
aid in forcing it down the gullet. They are solid and harmless 
teeth, as far as venom is concerned. To render’ a Puff Adder 
harmless the front fangs and the duplicate sets must all be 
removed, as well as the anterior maxillary bone, otherwise more 
will develop in time. 
How THEIR YOUNG ARE Born. 
Eggs are developed within the body of the female Puff Adder. 
These grow full size and incubate within the body. They lie in 
two long rows on each side of the backbone. Each snake is 
enveloped by a thin transparent skin. There are two vaginas, 
which join at the vent. The young lie one above the other along 
these vaginal tubes. They are born fully developed, and come 
forth coiled up within a transparent membraneous sac, which 
their active struggling soon ruptures, and they crawl away and 
henceforth lead an existence quite independent of the mother. 
