NATURAL HISTORY NOTES 
137 
The correspondence in Nature Notes alwut the ejeclive instinct of the 
young cuckoo discloses but one sceptic, and, in view of Dr. Sharpe’s treatment 
in “ Wonders of the Bird World,” and recent references to the subject elsewhere, 
the affirmative argument has, perhaps, been sufficiently maintained. But a few 
words about Edward Jennet’s paper, published in the Philosophical Transactions 
of the Royal Society for 1788, seem to be required. Jenner’s credit has been 
bl.isted by Waterton : his account has been neglected by Dr. Sharpe ; and his 
biographer, Dr. Norman Moore, in the “ Dictionary of National Biography,” a 
compilation of repute, in his wish to reconcile his own scepticism with the 
veracity of Jenner, has been enabled to declare that the account “is clearly 
not the result of Jenner’s own observations.” The passage is : “ The peculiarities 
of the cuckoo’s habits are ably discussed, but the account of the cuckoo 
removing the young hedge-sparrows is clearly not the result of Jenner’s 
own observation, and Waterton has demonstrated its absurdity. The explana- 
tion appears to be that Jenner employed a boy, his nephew Henry, to make 
these observations, who, too indolent to watch, gave an imaginary report.” 
Now it will surprise any one, on reading Jenner’s paper, to find that so far 
from the account being “clearly not the result of Jenner’s own observation,” 
nothing can be more clear than that it is — or, to be precise, — profe.sses to be. 
For example : “ The nest,” he writes, “ was placed so near the extremity of a 
hedge that / could distinctly see what was going forward.” 
Jenner describes five cases of observation of nestling cuckoos. In four he is 
himself the observer : in one he is not, and is careful to point out the defect. 
The evidence in this case is, however, not relevant to the question of ejection. 
The circumstances were as follows : — It had been suggested, as a cause of the 
parasitic habit of the cuckoo, that its form was not adapted to incubation. As a 
test Jenner, in the summer of 1786, placed two wagtails’ eggs in a nest with a 
young cuckoo about a fortnight old, and, the nest being at some distance from 
his house, set a person to watch. On the ninth day he was told that the eggs 
were hatched. He went and saw the broken shells, but no young wagtails. He 
adds: “The fact, therefore, of the birds being hatched I do not give you as 
coming immediately under my own eye, but the testimony of the person 
appointed to watch the nest was corroborated by that of another witness.” At 
this time Jenner did not suspect the young cuckoo of throwing out its com- 
panions. It may be asked. Why did not this young cuckoo throw out the wag- 
tails’ eggs ? Also other questions might be asked if the case were worth regarding 
apart from its evidence of Jenner’s desire for accuracy. 
Is it possible that the person set to watch the wagtails’ eggs has become the 
indolent and imaginative boy of Dr. Moore’s “explanation”? 
Of the four cases in which Jenner was himself the observer, in one he actually 
saw the process of ejection : in the others he noticed facts which are circum- 
stantial evidence of ejection. As the Philosophical Transactions for 1788 are 
not very readily accessible a summary of his account may be acceptable. 
On June 20, 1786, Jenner noticed that a cuckoo’s egg in a hedge-sparrow’s 
nest, which was under observation, had been hatched. The young cuckoo was 
the sole occupant of the nest, a young hedge-sparrow lying dead on the ground, 
and a hedge-sparrow’s egg being caught in the material of the outside of the 
nest. The egg was put back, again ejected, and again saved in the same manner. 
The cuckoo was then taken out and the egg put back. A quarter of an hour 
afterwards the egg was hatched and the young bird “ warm and lively.” Three 
hours after that the cuckoo was put back. The young hedge-sparrow was then 
ejected. It was restored, and again ejected. After each experiment Jenner 
retired, the old birds being anxious and fearful. 
On June 18, 1787, Jenner examined the nest of a hedge-sparrow containing 
one cuckoo’s and three hedge-sparrows’ eggs. On the day following the eggs 
were hatched, but the nest only contained one hedge-sparrow besides the cuckoo. 
This is the “leading case,” and I quote Jenner’s own words: — “The nest was 
placed so near the extremity of a hedge that I could distinctly see what was 
going forward in it. The little animal, with the assistance of its rump and 
wings, contrived to get the bird upon its back and, making a lodgment for the 
burden by elevating its elbows, clambered backward with it up the side of the 
nest till it reached the top, where, resting for a moment, it threw off its load with 
