156 THE BIRDS OF SHERWOOD FOREST. 
deposition, when the act is a very rapid one. How then 
could a sight of the eggs in a nest alter the colour of her 
egg already matured ? 
Dr. Baldamus finally gives up this conclusion in 
favour of the second, which I think is as unsupported as 
the first. Of course he admits that all the thirty- 
seven kinds of cuckoos are specifically identical as 
Cuculus canorus, and yet in one important point, 
the colour of the eggs they lay, he alleges they are 
specifically distinct. I cannot, I confess, understand 
such an anomaly. The thirty-seven kinds are identical 
in structure, plumage, and size, and yet each lays a 
differently marked egg. But are we to suppose that 
these thirty-seven kinds, visit a country at the same time, 
feed on the same food, mingle-in the same hedgerows, 
and yet do not breed together? The idea is incredible, 
and yet the crossing- which must of necessity take place 
between these imaginary kinds, would of course destroy 
in time the alleged distinctive markings of the eggs their 
progeny would produce, and-bring all to one uniform 
character. 
I have dwelt at length on-this subject, which is one 
of great interest, but I must say that I should like 
clearer proof than-I at. present possess, before I can 
accept either conelusion.. All who possess the oppor- 
tunity should lend their aid. in its investigation, and 
accumulate such evidence as will either disprove the 
theory, or make us willing to give up our long-cherished 
opinions. 
The first point evidently is, do the eggs of the cuckoo 
vary to the extent asserted? I believe they do not; 
and to this our observations should be directed, and 
nothing but positive evidence admitted. 
