HETEROCHROSIS IN ESSEX BIRDS AND THEIR EGGS. 201
the pale blue unspotted type of egg in the school grounds
at Felsted. In 1912 there were two such birds. In 1911
a pair raised a brood from eggs of the pale blue variety.
In 1912 in the same place there were two nests within forty,
yards of each other and in each nest were light blue eggs
from which broods were raised. The point is made that
the colour of the egg may be inherited. Ref.: Felsted
School Scien. Soc. Report No. 25; British Birds (Mag.),
vol. 6, p. 343.
British Hedge-Sparrow. Prunella modularis occidentalis (Hart.).
Nest with eggs all well spotted with black at the large end
at Felsted in 1910. Ref.: Felsted School Scien. Soc. Re-
port No. 25.
Lapwing. Vanellus vanellus (L.).
An egg, ground-colour likened to that of a Starling's egg,
found, not near a nest, on 1st April, 1915, between They-
don Bois and Abridge. The dark markings were smaller
than is usual in normal specimens. Ref.: The Essex Nat.,
vol. 18, p. 105.
It would require some boldness to correlate the origin of
heterochrosis in birds and of the phenomenon in their eggs. Al-
though we feel that this at the present stage could not be justified,
yet it seems that the question should at least be raised. Adher-
ing to the practical plan adopted it would be of interest to know
if birds exhibiting abnormal plumage lay abnormal eggs. Ob-
servations of the eggs of albinistic birds, for example, would give
results of some value. Leaving the question of origin alone, there
are some very broad resemblances between the manner in which
eggs and plumages are affected. Weakness of the pigment-
producing factor results in albinistic eggs and plumages and some
variation, perhaps excess, of this in both cases results in abnormal
red colouration. There are certain plumage variations, such as
the hepatic Cuckoo and the rufous partridge, Perdix montana,
which although variable possess broad resemblances by which they
can be recognised. Analogies are found in eggs, for the ery-
thristic egg of the Lapwing and the pale blue unspotted egg of the
Spotted Flycatcher are both known to oologists. It may be re-
marked, however, that plumage may be more resistent to aberra-
tion than eggs,as for example the great range of variation in the
eggs of the Tree Pipit. It has been shown that the tendency