482 
Bulletin No. 1G2.—1915. 
about. The only experiments on wild species which normally lay 
a restricted number that we have found mentioned are some tests 
which Levick (1914, p. 127) made in the Antarctic with McCormick’s 
Skua (Megalestris maccormicki ) . As in the pigeon the normal com¬ 
plement of this gull is only two eggs. Levick says: “In order to 
find out how many eggs a Skua would lay, I marked some nests, and 
took the eggs as they were laid. In each case a second egg was laid, 
but when this was taken no more appeared. In two nests I removed 
the first egg as soon as it was laid, but left the second, which was then 
sat upon by the parent, who was content with it, or unable to lay a 
third.” It would appear that in birds which normally lay so few 
eggs at a time, the stimulus for further production caused by remov¬ 
ing the eggs, does not occur early enough to allow for continuous 
production. 
Considering the matter from a genetic or phylogenetic standpoint, 
it would bo surprising if a definite relationship of sex to the two eggs 
of the set were to have become established in one group of pigeons 
and not in all. This can hardly be the case, however, for while two 
is the usual number there is apparently no uniformity in this respect 
in different members of the family Columbidae, or even within the 
genus Columba. The Red-billed Pigeon ( Columba Jlavirostris ), for 
example, is reported to lay but a single egg at each nesting; the 
Passenger Pigeon ( Ecto pistes migratorius ) , formerly so abundant in 
North America, but now extinct, ordinarily laid but a single egg, but 
sometimes laid two; the Blue-headed Quail-dove (Starnoenas cyano- 
cephala) lays one or two; while it is stated that the Mourning Dove 
(Zenaidurn macrourn) may even lay three or four (Davie, 1889, p. 
157). Inglis (1899) reports the laying of three eggs in a nest by a 
Bengal Green Pigeon (C. phoenicopterus ) . These records are from 
nests taken in the open, so of course the possibility of the extra eggs 
having been laid by a different female cannot be entirely excluded. 
The relation which the popularly assumed facts, if true, might bear to 
practical pigeon breeding is illustrated by directions which appeared 
in a pigeon paper a few years ago for enabling the breeder to maintain 
