Transitory Tooth in Young Snakes. 37 



The power of the young cuckoo to eject the eggs 

 and true birds from the nest, we say again, is really 

 not more wonderful than the power of the newly- 

 hatched dabchick for diving, swimming, etc., though 

 the results of the efforts are so very different, or of 

 the newly-hatched hoatzin to travel considerable 

 distances by aid of its hooked thumbs chiefly. 



Mr. Darwin was of this opinion, and these cases of 

 ours above only support and give force to his, if, 

 indeed, they are not more apt as dealing with birds : 



" The first step towards the acquisition of the 

 proper instinct might have been mere unintentional 

 restlessness on the part of the young bird, when 

 somewhat advanced in age and strength ; the habit 

 having been afterwards improved and transmitted to 

 an earlier age. I can see no more difficulty in this 

 than in the unhatched young of other birds acquiring 

 the instinct to break through their own shells ; or 

 than in young snakes acquiring in their upper jaws, 

 as Owen has remarked, a transitory sharp tooth for 

 cutting through the tough eggshell." {Origin, p. 214.) 



Cannock Brand {Longman's, June, 1891,) tries hard 

 to explain the preponderance of cuckoo males by the 

 fact of the males of all birds being most restless in the 

 nest. But this for reasons we are prepared to give is 

 certainly not exhaustive and final, if, indeed, it has 

 any ground ; and when he says that it seems " still 

 probable that the cuckoo sometimes lays in the nest," 

 we need only point to the fact that the shorter time 

 spent near the victimised nest is of the very essence 

 of success — the more, if besides depositing the egg, 

 there is an effort made generally to extrude one of the 

 true eggs from it. 



