lyS The Natural History 



and that the air, when loaded with fogs and vapours, 

 and even with copious dews, can alone advance a con- 

 siderable and never-failing resource. Persons that are 

 much abroad, and travel early and late, such as shepherds, 

 fishermen, etc., can tell what prodigious fogs prevail in 

 the night on elevated downs, even in the hottest parts of 

 summer ; and how much the surfaces of things are 

 drenched by those swimming vapours, though, to the 

 senses, all the while, little moisture seems to fall. 



I am, etc. 



LETTER XXX 



TO THE HONOURABLE DAINES BARRINGTON 



Selborne, April 3, 1776. 



Dear Sir, 

 Monsieur Ilerlssant, a French anatomist, seems per- 

 suaded tliat he has discovered the reason why cuckoos 

 do not hatch their own eggs ; the impediment, he 

 supposes, arises from the internal structure of their parts, 

 which incapacitates them for incubation. According to 

 this gentleman, the crop or craw of a cuckoo does not 

 lie before the ster?ium at the bottom of the neck, as in 

 the gaUi}ice, coiiuiibce^ etc., but immediately behind it, on 

 and over the bowels, so as to make a large protuberance 

 in the belly.^ 



Induced by this assertion, we procured a cuckoo; and, 

 cutting open the breast-bone, and exposing the intestines 

 to sight, found the crop lying as mentioned above. This 

 stomach was large and round, and stuffed hard like a 

 pin-cushion with food, which, upon nice examination, we 

 found to consist of various insects ; such as small scarabs, 

 spiders, and dragon-flies ; the last of which we have seen 

 cuckoos catching on the wing as they were just emerging 

 out of the aurelia state. Among this farrago also were 

 to be seen maggots, and many seeds, which belonged 

 either to gooseberries, currants, cranberries, or some such 

 ^ Histoirc dc V Acad^mie Royale, 1752. 



