202 NATURAL HISTORY OF SELBORNE. 



LETTER XXX. 



TO THE SAME. 



SELBORNE, April yd, 1776. 



DEAR SIR, Monsieur Herissant, a French anatomist, seems 

 persuaded that 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 sternum at the bottom of the neck, 

 as in the galince, colomba* &c., 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 pincushion, 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 fruit ; so that these birds appa- 

 rently subsist on insects and fruits ; nor was there the least 

 appearance of bones, feathers, or fur, to support the idle notion of 

 their being birds of prey. 



The sternum in this bird seemed to us to be remarkably short, 

 between which and the anus lay the crop, or craw, and immediately 

 behind that the bowels against the back-bone. 



It must be allowed, as this anatomist observes, that the crop 

 placed just upon the bowels must, especially when full, be in a very 

 uneasy situation during the business of incubation ; yet the test 

 will be to examine whether birds that are actually known to sit for 

 certain are not formed in a similar manner. This inquiry I pro- 

 posed to myself to make with a fern-owl, or goatsucker, as soon as 

 opportunity offered : because, if their formation proves the same, 



* Histoire de I'Acadciine Rcyale, 1752. 



