222 THE ZOOLOGIST. 
the two others. It was very like a Chaffinch’s egg, of a greyish 
green ground colour, sparingly marked with smaller reddish and 
larger reddish brown spots, and was remarkable as being thickly 
spotted at the smaller end instead of the larger. It was not quite 
so large as a Chaffinch’s egg.” 
Of the brittleness of the third and smallest egg the observer 
says, “ On finding the young Cuckoo, the two unincubated eggs, 
the reddish brown one and the small one, lay by the side of the 
nest. The first was crushed in and appeared to be rotten, the 
second was uninjured, but on attempting to blow it subsequently, 
he found that it was unfertilized, and only contained a partly 
dried-up and wasted yolk. No doubt, like the injured one, it was an 
egg dropped during the time of sitting, and not fully developed 
nor fecundated, as was apparent from its inferior size, very thin 
shell, and small contents.” 
An “extremely brittle and thin shell” (as I have before 
remarked) is not possessed by any Cuckoo’s egg, whether large 
or small; on the contrary, no egg of any of the foster-parents of 
the Cuckoo has such a hard and dense shell as that of the 
Cuckoo itself. If the small egg was so heavily coloured as the 
observer states, it must have been also fully formed, for the 
colour is the last stage in the development of the egg as regards 
the shell. 
Already, in 1880, Dr. Kutter, and then Herr Hauptmann 
Kriger-Velthusen, simultaneously with myself, drew attention to 
the unusual hardness and firmness of the Cuckoo’s egg (see Orn. 
Centralb. 1880), and subsequently I wrote, in the 9th Jahres- 
bericht of the ‘ Ausschuss fir die Beobachtungsstation der Vogel 
Deutschlands’ (p. 201), concerning a Cuckoo’s egg found here in 
Cassel in 1884, in which the beak of the young Cuckoo was to 
be seen through the egg. This Cuckoo’s egg (which was already 
perforated by the embryo so that the beak of the young one 
was visible as a small point) was found in the accidentally 
destroyed nest of a Hedgesparrow, Accentor modularis, with four 
well-incubated eggs of that bird. Yet twelve days afterwards 
I was able to empty the egg artificially without breaking it, and 
it now rests in my collection as a proof of the hardness and 
firmness of the Cuckoo’s egg. On the other hand, the much- 
incubated eggs of the Hedgesparrow broke on the first attempt 
to blow them. Not to digress too much from my task of 
