The Zoologist— May, 1873. 3509 



touch tbequestion. A good many people who have only read hastily, 

 and still more those who have to all appearance only read at second 

 or third-hand what has been written on the subject, seem to 

 imagine that the Doctor has wished to assert that the cuclvow 

 can voluntarily influence the colour of her egg, so as to assimilate 

 it to those already in the nest in which she is about to deposit it.* 

 Dr. Baldamus, indeed, mentions such a supposition, but expressly 

 says that he rejects it, and herein 1 think that nearly every physio- 

 logist will agree with him. 



It will be admitted, I think, that Dr. Baldamus's inference as to 

 the object of the practice being that the cuckow's egg should be 

 " less easily recognised by the foster-parents as a substituted one," 

 is likely to be true. This being the case, only one explanation of 

 the process can to my mind be offered. Every person who has 

 studied the habits of animals with sufficient attention will be con- 

 versant with the tendency which certain of those habits have to 

 become hereditary. It is, I am sure, no violent hypothesis to sup- 

 pose that there is a very reasonable probability of each cuckow 

 most commonly placing her eggs in the nests of the same species 

 of bird, and of this habit being transmitted to her posterity. With- 

 out attributing any wonderful sagacity to the cuckow, 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 another 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 cuckow 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 

 cuckow which always placed her egg in a reed-wren's or titlark's 

 nest doing the like. 



Furtlier, I am in a position to maintain positively that there is a 

 family likeness between the eggs laid by the same bird, even at an 

 interval of many years. I know of more than one case in which a 



* Thus Mr. Cecil Smith (not to be confounded with Mr. A. C. Smith, before men- 

 tioned) in a work published within the last few weeks, falls into this mistake 

 (" Birds of Somersetshire," p. 265), after having stigmatised the Doctor's theory as 

 " wild," which he well might if it had been as it is represented. 



SECOND SERIES— VOL. VIII. 2 



