•2 26 Mr. Jennjer’s Obfervatiom on the 
fimilar procefs, was conveyed to the edge of the neft, and 
thrown out. Thefe experiments I have fmce repeated feveral 
times in different nefts, and have always found the young 
Cuckoo difpofed to act in the fame manner. In climbing lip 
the ne ft, it fometimes drops its burden, and thus is foiled in 
its endeavours ; but, after a little refpite, the work is re- 
fumed, and goes on almoft inceftantly till it is effected. It is 
wonderful to fee the extraordinary exertions of the young 
Cuckoo, when it is two or three days old, if a bird be put 
into the neft with it that is too weighty for it to lift out. In 
this Hate it feems ever reftlefs and uneafy. But this difpofi- 
tion for turning out its companions begins to decline from the 
time it is two or three till it is about twelve days old, when, 
as far as I have hitherto feen, it ceafes. Indeed, the difpoft- 
tion for throwing out the egg appears to ceafe a few days 
fooner ; for I have frequently feen the young Cuckoo, after it 
had been hatched nine or ten days, remove a nettling that had 
been placed in the neft with it, when it fuffered an egg, put 
there at the fame time, to remain unmolefted. The lingu- 
larity of its fhape is well adapted to thefe purpofes ; for, dif- 
ferent from other newly-hatched birds, its back from the Jca- 
pula downwards is very broad, with a confiderable depreftion 
in the middle. This depreftion feems formed by nature for 
the deiign of giving a more fecure lodgement to the egg of 
the Hedge-fparrow, or its young one, when the young Cuckoo 
is employed in removing either of them from the neft. When 
it is about twelve days old, this cavity is quite filled up, and 
then the back affumes the fhape of nettling birds in general. 
Having found that the old Hedge-fparrow commonly throws 
out feme of her own eggs after her neft has received the 
Cuckoo’s, and not knowing how (he might treat her young 
2 ones, 
