BLENDED ORIGIN, OR PLASTICITY OF INSTINCT. 209 



to meet them by intelligent adjustment, which, if continued 

 sufficiently long and aided by selection, would pass into true 

 instincts of building combs in new directions, of support- 

 ing combs during their construction, of carding threads of 

 cloth, of substituting cement for propolis, or oatmeal for 

 pollen. 



Were it necessary, other instances of the plasticity of 

 instinct could be drawn from bees and likewise from ants,* 

 but quitting now the Hymenoptera, I shall pass to other 

 animals. 



Dr. Leech gives/f on the authority of Sir J. Banks, a case 

 of a web-spinning spider which had lost five of its legs, and, 

 as a consequence, could only spin very imperfectly. It was 

 observed to adopt the habits of the hunting spider, which 

 does not build a web, but catches its prey by stalking. This 

 change of habit, however, was only temporary, as the spider 

 recovered its legs after moulting. But it seems evident from 

 this case that, so far as the plasticity of instinct is concerned, 

 the web-spinning spider would be ready at any time to adopt 

 the habit of hunting, if for any reason it should not be able 

 to build a web — and tin's even by way of sudden transition 

 in the life-time of an individual. 



Coming now to vertebrated animals, we may easily find 

 that the same principles obtain in them. And here, for the 

 Bake of brevity, I shall confine myself to instances drawn 

 from the oldest, most constant, and, therefore, presumably the 

 most fixed of the instincts which vertebrated animals display, 

 viz., the maternal. 



With regard to Birds, I showed in the preceding chapter 

 that individual variations of nest-building are not uncommon. 

 We have now to remark that such variations, or deviations 

 from the ancestral modes, are not always the result of mere 

 caprice, but sometimes of intelligent purpose. In order to 



• See Animal Intelligence, from which I may specially quote the follow- 

 IBg, in order to show briefly that ants (juito us much as. «>r more than lavs, 

 I nl 11 " ni"\ ing harmony " in the construction of their architect lire s— 



• The characteristic trait of the building of ants," s:i\^ ETorel, " is the almost 

 tompli te absence of an unchangeable model peculiar to each species, snob as 

 i- found in wasps, bees, and others. The ants know how bo iml their indeed 

 hole perfect work to circumstances, and to take advantage of each situation. 

 Us, each works for itself on a given plan, and is onl\ ocoaeionallj aidi d 

 bj others when they onderstand its plan" (p. 129). 



+ Transactions Linn. 8oe., roL u, p. 898, This case is briefly alluded to 

 bj Mr. Darwin in the Appendix* 



