LOCAL AND SPECIFIC VARIETIES OF INSTINCT. 255 



particular species or genus in question, after that species or 

 genus had branched off from the more ancestral type. Now- 

 such cases of specific instinct are by no means rare — cases, 

 I mean, like that of the Californian Woodpecker (Melancrpes 

 formicivmnis), which displays the curiously distinctive instinct 

 of storing acorns in the crevices of the bark of the yellow 

 pine {Pinus pondcrosa) for future food, wdiile no otlier species 

 of woodpecker shows any tendency to such a habit.* JKit 

 such cases of instinct peculiar to one species or genus are so 

 common that I feel it would be needless to enumerate them, 

 in view of the more conclusive cases just given — cases more 

 conclusive because the obsolete instincts happen to have been 

 of a kind requiring special corporeal structures for their 

 operation, which now survive tlieir ancestral uses.f Lastly, 

 we must not forget the important fact that we are far from 1 

 being wholly without evidence of the transmutation of instinct I 

 taking place under actual observation — as in the case of the \ 

 ducks in Ceylon having quite lost their natural instincts I 

 with regard to w^ater (in this resembling the upland geese), ' 

 sparrows and swallows building on houses instead of on ti-ees, 

 insects, birds and mammals which normally feed on vegetable 

 substances suddenly becoming carnivorous, &c., &c. ; for all 

 these cases of local varieties of instinct are really so many 

 cases of racial varieties, and the step between this and specific 

 varieties is clearly not a large one. 



* According to Mr. C. J. Jackson (Proc. Boston Kaf. Hist. Soc, vol. x, 

 p. 227) the acorns selected for storing are only those which are infested with 

 maggots, which serre as food for the young in the following spring ; and the 

 acorns are driven into holes specially prepared for them, and which fit so 

 well that the maggots when they come to maturity are unable to escape — 

 being therefore imprisoned in a larder until they are required for the use of 

 the young birds. See also J. K. Lord's Katuralist in Vancouver's Island, 

 vol. i, Dp. 289-92, and T/ie Ibis, 1868. 



t The most suggestive of this class of cases are those in which the species 

 which exhibits the instinct peculiar to itself happens to have become dis- 

 persed over wide geographical areas since the instinct arose, and leing there- 

 fore now found in different parts of the world, living under different 

 conditions of life, and yet retaining the same peculiar instinct. Thus, for 

 instance, "in all quarters of the globe species of trap-door spiders are found 

 occurring in more or less localized areas," and the harvesting ants of Europe 

 and America belong to the same genus. The South American Thrush lines 

 its nest with mud in the same way as does our own Thrush, tlie Hornbills of 

 Africa and of India in tlieir nidification show the same peculiar instinct of 

 imprisoning their hens in holes of trees with plaster, &c., &c. 



