192 NATURAL HISTORY OF SELBORNE. 



Monsieur Herissant's conjecture, that cuckoos are incapable of 

 incubation from the disposition of their intestines, seems to fall 

 to the ground : and we are still at a loss for the cause of that 

 strange and singular peculiarity in the instance of the cuculus 

 canorus.* 



We found the case to be the same with the ring-tail hawk, in 

 respect to formation; and, as far as I can recollect, with the 

 swift ; and probably it is so with many more sorts of birds that 

 are not granivorous. 



I am, &c. 



LETTER XXXI. To THE HON. DAINES HARRINGTON. 

 DEAR SIR, Selborne, Apicil 29, 1776. 



ON August the 4th, 1775, we surprised a large viper, which 

 seemed very heavy and bloated, as it lay in the grass basking 

 in the sun. When we came to cut it up, we found that the ab- 

 domen was crowded with young, fifteen in number ; the shortest 

 of which measured full seven inches, and were about the size of 

 full-grown earth-worms. This little fry issued into the world 

 with the true viper-spirit about them, showing great alertness 

 as soon as disengaged from the belly of the dam : they twisted 

 and wriggled about, and set themselves up, and gaped very wide 

 when touched with a stick, showing manifest tokens of menace 

 and defiance, though as yet they had no manner of fangs that we 

 could find, even with the help of our glasses. 



To a thinking mind nothing is more wonderful than that early 

 instinct which impresses young animals with the notion of the 

 situation of their natural weapons, and of using them properly 

 in their own defence, even before those weapons subsist or are 

 formed. Thus a young cock will spar at his adversary before his 

 spurs are grown ; and a calf or a lamb will push with their heads 

 before their horns are sprouted. In the same manner did these 

 young adders attempt to bite before their fangs were in being, f 



* This most singular habit of the cuckoo is not to be accounted for upon any structural pecu- 

 liarities, as there are genera closely allied to it which incubate their own eggs ; while on the 

 other hand the same habit is observable in a bird of a very different family, the "cow-bunting" 

 of Wilson, one of the starling tribe. All proiferred explanations must therefore fall at once to 

 the ground, if not applicable alike to both. ED. 



t A still more extraordinary instinct is that which guards an animal against the weapons or 

 mode of attack, of an antagonist. This may be noticed in a thousand instances, but in none 

 more strikingly than in the manner a rat defends itself from a ferret, being perfectly aware that 



