434 SNAKES. 



Heat and moisture are essential to the hatching of eggs. 

 When at liberty the snake selects some spot among decaying 

 leaves, or in a manure heap where decomposition produces 

 sufficient warmth. In the tropics, where the sun's rays alone 

 suffice, a soft moist bed is more easily found, and here it is 

 that immense broods are produced. 



The period of gestation can scarcely be pronounced upon 

 with certainty. It depends not only on the size of the 

 snake, but on the degree of warmth that can be enjoyed as 

 an assistant to mature the eggs. Schlegel mentions three 

 or four months from copulation to the laying of eggs in the 

 species indigenous to France. But as other circumstances 

 combine to cause variations in these periods, it is very 

 unsafe to fix upon the precise time of gestation. 



Says Rymer Jones, * Reptiles do not sit {sic) upon their 

 eggs, hence the latter have only a membranous envelope. 

 In many of the reptiles which lay eggs, especially the 

 Colubri (colubrine snakes), the young one is already formed 

 and considerably advanced in the ^g^ at the moment when 

 the mother lays it ; and it is the same with those species 

 which may at pleasure be rendered viviparous by retarding 

 their laying.'^ The latter words are traced to Cuvier, and 

 prove that this most remarkable power has long been 

 recognised. 



In the first few words of the above, Jones spoke of 

 reptiles generally from toads to turtles ; with the latter, 

 soft eggs would certainly fare badly did they attempt to 

 incubate them. Still the term * reptiles ' is misleading, 

 because, as is now well known, some snakes do incubate, 



■^ Ar'dcle ' Reptilia ' in Todd's EncyclopiEdia of Anatomy, vol. iv. pt. i. p. 264. 



