16 VENOMS 



" Nature," write Dumeril and Bibron, " seems to have caused 

 the tints and colours of snakes to vary in accordance with their 

 habits and modes of Hfe. Generally speaking, the colours are 

 greyish or dull in species that are wont to live among sand, or 

 which bury themselves in loose earth, as also in those that lie 

 in wait on the trunks or large boughs of trees ; while these hues 

 are of a bluish-green, resembling the tint of tbe leaves and young 

 shoots of plants, in snakes tbat climb among bushes or balance 

 themselves at the end of branches. It would be difficult to describe 

 all the modifications revealed by a general study of the colours of 

 their skins. Let us imagine all the effects of the decomposition of 

 light, commencing with white and the purest black, and passing on 

 to blue, yellow, and red ; associating and mixing them together, 

 and toning them down so as to produce all shades, such as those 

 of green, of violet, with dull or brilliant tints more or less pro- 

 nounced, and of iridescent or metallic reflections modified by spots, 

 streaks, and straight, oblique, undulating, or transverse lines. Such 

 is the range of colours to be found in the skin of snakes." 



This skin is covered by a thick epidermis, which is periodically 

 detached in its entirety, most frequently in a single piece. Before 

 effecting its moult, the reptile remains in a state of complete repose 

 for several weeks, as if asleep, and does not eat. Its scales grow 

 darker and its skin becomes wrinkled. Then one day its epidermis 

 tears at the angle of the lips. The animal thereupon wakes up, 

 rubs itself among stones or branches, divests itself entirely of its 

 covering as though it were emerging from a sheath, and proceeds 

 forthwith in quest of food. 



The moult is repeated in this way three or four times every year. 



