16 THE SNAKES OF SOUTH AFRICA. 
lunge out wildly with gaping jaws, but owing to their semi-blind 
condition their aim is not accurate. 
When molested, a snake darts out and vibrates its tongue, 
evidently with the purpose of intimidating its enemy. 
CHANGING THE SKIN. 
Snakes change their skins several times a year before reaching 
the adult state. Adult snakes usually only change their skins 
once, sometimes twice during a season, sometimes only once in 
two seasons. At least, this is so in captivity, as I have had ample 
opportunity of ascertaining. The first skin-shedding process 
takes place a few days after birth. 
Fic. 8.—Cast skin of head and neck of snake. Note inverted eye scales, like watch glasses 
with concave side uppermost. 
The shedding or casting of the old skin begins at the lips. 
The skin around the mouth curls up, and by pushing itself against 
twigs, crawling through tufts of grass, etc., the snake gradually 
draws itself right out of its skin. This comes off inside out, like 
a tight glove being pulled off the hand from the wrist portion. 
The cast skin is often perfect, without a crack, tear, or loss of 
a single scale—even the transparent eye scales come away. The 
main reason why snakes cast their skins is to provide for increased 
growth. The skin of a snake does not grow with the growth of 
the body, as is the case with warm-blooded animals. So, when it 
