208 n a t u r a l h i s t o r y
L E T T E R XX X.
TO TH E S A M E .
D E A R S IR , S e l b o r n e , April 3, 1776'
JVIonsieur H eris sant, a French anatomift, feems perfuaded
that he has difcovered the reafon why cuckoos do not hatch their
own eggs; the impediment, he fuppofes, arifes from the internal
ftrudture of their parts, which incapacitates them for incubation.
According to this gentleman, the crop, or craw, of a cuckoo does
mot lie before the fternum at the bottom of the neck, as in the
gallina, columba, &c. but immediately behind it, on and over the
bowels, fo as to make a large protuberance in the belly0.
Induced by this affertion, we procured a cuckoo; and, cutting
open the breaft-bone, and expofing the inteftines to fight, found
the crop lying as mentioned above. This ftomach was large and
round, and fluffed hard like a pincufhion with food, which, upon
nice examination, we found to confift of various infefts; fuch as
fmall fcarabs, fpiders, and dragon-flies; the laft of which we have
feen cuckoos catching on the wing as they were juft emerging out
of the aurelia ftate. Among this farrago alfo were to be feen
maggots, and many feeds, which belonged either to goofeberries,
currants, cranberries, or fome fuch fruit; fo that thefe birds ap-
Hifioire de VAcademic Royak, 175*.
parently
O F S E L B O R N E. 209
parently fubfift on infedts and fruits: nor was there the leaft appearance
of bones, feathers, or fur, to fupport the idle notion of
their being birds of prey.
The fternum in this bird feemed to us to be remarkably fhort,
between which and the anus lay the crop, or craw, and immediately
behind that the bowels againft the back-bone.
It muft be allowed, as this anatomift obferves, that the crop
placed juft upon the bowels muft, efpecially when full, be in a
very uneafy fituation during the bufinefs of incubation; yet the
teft will be to examine whether birds that are actually known to
fit for certain are not formed in a fimilar manner. This inquiry
I propofed to myfelf to make with a fern-owl, or goat-fucker, as
foon as opportunity offered: becaufe, if their formation proves the
fame, the reafon for incapacity in the cuckoo will be allowed to
have been taken up fomewhat haftily.
Not long after a fern-owl was procured, which, from it’s habit
and ftiape, we fufpefted might refemble the cuckoo in it’s internal
conftrudtion. Nor were our fufpicions ill-grounded; for, upon the
diffe&ion, the crop, or craw, alfo lay behind the fternum, immediately
on the vifcera, between them and the ikin of the belly. It was
bulky, and fluffed hard with large phalanx, moths o f feveral forts,
and their eggs, which no doubt had been forced out of thofe infects
by the adtion of fwallowing.
Now as it appears that this bird, which is lb well known to
pradtife incubation, is formed in a fimilar manner with cuckoos
Monfieur Heriffant’s conjedture, that cuckoos are incapable of incubation
from the difpofition of their inteftines, feems to fall to the
ground ; and we are ftill at a lofs for the caufe of that ftrange and
Angular peculiarity in the inftance of the cuculus cano'rus.
E We