CHAPTER XYIII 



HOW EEPTILES PEODTJCE THEIR TOUNG — mCTJBATION OF 



EGGS BT THE PYTHONS OTIPAEOUS AND OVOVI- 



VIPAEOrrS SNAKES THE NTJMBEES OE TOXTNG PEO- 



DUCED HOW LONG EEPTILES LITE THE BIOG- 



EAPHT OF A EATTLESNAKE 



The majority of reptiles lay eggs which are left 

 to hatch from the heat of the sun, or by the decom- 

 position of vegetable matter in which they are de- 

 posited. Among the snakes there are a few excep- 

 tions to the rule of leaving the eggs unprotected. 

 The species comprising the genus Python incubate 

 their eggs by coiling closely about them. During 

 this action on the part of the female snake a strange 

 thing happens. The body of the ordinarily cold- 

 blooded reptile assumes a much higher temperature 

 than the surrounding atmosphere ; this rise in tem- 

 perature is often as great as twenty degrees. After 

 the period of incubation, which varies from six to 

 eight weeks, has passed, the serpent's body gradually 

 acquires the temperature of the surrounding air. 

 When the little pythons have once hatched they are 

 fully able to care for themselves, and the mother 

 pays no further attention to them. 

 173 



