REPTILES AND THEIR PROGENY i6i 



development of the young always proceeds forthwith 

 without interruption, save in one or two exceptional 

 instances. In the lizard-like tuatera of New Zealand the 

 eggs are laid during the Southern summer — between 

 November and February — and by August, in the case of 

 the earlier eggs, contain ripe embryos. But these do not 

 hatch out till the following February — or until the em- 

 bryos are some thirteen months old. Thus these embryos 

 undergo a period of hibernation such as is common to 

 many animals which have to evade starvation during the 

 time when the food supply necessary to their sustenance 

 is no longer attainable; migration to attain this end is 

 the only other alternative, and this is impossible. A 

 precisely similar instance of embryonic hibernation ob- 

 tains in the case of the European pond tortoise (Emys 

 orbicularis). But only in the northern part of its range — 

 in Russia, for instance — the embryonic stage extends over 

 a period of no less than eleven months ; where the winters 

 are mild, as in southern Europe, the young hatch out the 

 same autumn. In the common chamaeleon, again, the eggs 

 are laid in October, and do not hatch out till the following 

 February or March. 



During the last few years our knowledge of what we 

 may call the domestic life of birds has increased enor- 

 mously, affording us an insight into the deeper problems 

 of their life-history hitherto undreamed of. This know- 

 ledge has only been gleaned at the expense of infinite 

 patience, and occasionally some danger ; but that there 

 will ever arise an observer with sufficient patience to 

 follow up the daily life of any of the reptiles, seems almost 

 too much to hope for. But not till then shall we learn 

 the significance of the singular disparity in the number of 

 eggs laid by different species of these cold-blooded animals. 

 II 



