234 Habit and Instinct. 



of course, is not intended as a criticism of Mr. Wallace's 

 views concerning nest-building, since he does not regard 

 the habit as founded on a definitely instinctive basis. It 

 is a suggestion towards increased exactness in our technical 

 nomenclature which may be found generally useful. 



No doubt nest-building is subject both to variation of 

 congenital origin and to modification through experience. 

 Mr. Blackwall, in the first volume of the Zoological Journal, 

 says, " It is evident that birds of the same species possess 

 the constructive powers in very different degrees of perfec- 

 tion, for, though the style of the architecture is usually 

 adhered to, the nests of some individuals are finished in 

 a manner greatly superior to those of others ; " and he 

 quotes a case in which a yellow bunting failed to build at 

 all, depositing its eggs on the bare ground, in which situa- 

 tion she sat upon them till they were hatched.* Such 

 differences are probably due to variation. On the other 

 hand, modification may often occur. Bolton, in the preface 

 to his "Harmonia Euralis," says, "I observed a pair of 

 goldfinches beginning to make their nest in my garden on 

 May 10, 1792; they had formed the groundwork with 

 moss, grass, etc., as usual, but on my scattering small 

 parcels of wool in different parts of the garden, they in 

 a great measure left off the use of their own stuff, and 

 employed the wool. Afterwards I gave them cotton, on 

 which they rejected the wool, and proceeded with the 

 cotton ; the third day I supplied them with fine down, 

 on which they forsook both the others, and finished their 

 work with the last article. The nest, when completed, 

 was somewhat larger than is usually made by this bird, 

 but retained the pretty roundness of figure and neatness 

 of workmanship which is proper to the goldfinch." t Very 



* See Yarrell, " British Birds," vol. i. p. 491. 

 t Ibid., vol. i. p. 541. 



