And yet we must be satisfied on these points if we are to accept the ingenious theory of Dr. Baldamus. If we understand the learned German rightly, he states that, with a view to insure the preservation of species which would otherwise be exposed to danger, Nature has endowed every hen Cuckoo with the faculty of laying eggs similar in colour to those of the species in whose nest she lays, in order that they may be less easily detected by the foster parents, and that she only makes use of the nest of some other species (_i.e._ of one whose eggs do _not_ resemble her own) when, at the time she is ready to lay, a nest of the former description is not at hand. This statement, which concludes a long and interesting article on the subject in the German ornithological journal “Naumannia,” for 1853, has deservedly attracted much attention. English readers were presented with an epitome of this article by Mr. Dawson Rowley in the “Ibis” for 1865, and the Rev. A. C. Smith, after bringing it to the notice of the Wiltshire Archæological Society in the same year, published a literal translation of it in the “Zoologist” for 1868. More recently, an article on the subject, by Professor Newton, appeared in “Nature” and elicited various critical remarks from Mr. H. E. Dresser, Mr. Layard, and other ornithologists which deserve perusal.[102] To enter fully upon the details of this interesting subject would require more space than can here be accorded; one can only glance therefore at the general opinions which have been expressed in connection with it. If the theory of Dr. Baldamus be correct, is it possible to give a reasonable and satisfactory explanation of it? This question has been answered by Professor Newton in the article to which we have just referred. He says:—“Without attributing any wonderful sagacity to the Cuckoo, it does seem likely that the bird which once successfully deposited her eggs in a Reed Wren’s or a Titlark’s nest, should again seek for another Reed Wren’s, or a Titlark’s nest (as the case may be) when she had an egg to dispose of, and that she should continue her practice from one season to another. We know that year after year the same migratory bird will return to the same locality, and build its nest in almost the same spot. Though the Cuckoo be somewhat of a vagrant, there is no improbability of her being subject to thus much regularity of habit, and indeed such has been asserted as an observed fact. If, then, this be so, there is every probability of her offspring inheriting the same habit, and the daughter of a Cuckoo which always placed her egg in a Reed Wren’s or a Titlark’s nest doing the like.” In other words, the habit of depositing an egg in the nest of a particular species of bird is likely to become hereditary.