594 TEE POPULAR SCIENCE MONTHLY. 



ground, to build " new ones on the tops of high trees, afterward bring- 

 ing their young ones down on their backs to the water " ; and exactly 

 the same thing has been recorded by another observer of the wild ducks 

 of Guiana. Now, if intelligent adjustment to peculiar circumstances is 

 thus adequate, not only to make a whole breed or species of bird trans- 

 port their young upon their backs — or, as in the case of the woodcock, 

 between their legs — but even to make web-footed water-fowl build 

 their nests in high trees, I think we can have no doubt that if the need 

 of such adjustment were of sufficiently long continuance, the intelli- 

 gence which leads to it would eventually produce a new and remark- 

 able modification of their ancestral instinct of nest-building. 



Turning now from the instinct of nidification to that of incubation, 

 I may give one example to show the plasticity of the instinct in rela- 

 tion to the observed requirements of progeny. Several years ago I 

 placed, in the nest of a sitting Brahma hen, four newly-born ferrets. 

 She took to them almost immediately, and remained with them for 

 rather more than a fortnight, when I made a separation. During the 

 whole of the time the hen had to sit upon the nest, for the young fer- 

 rets were not able to follow her about, as young chickens would have 

 done. The hen was very much puzzled by the lethargy of her off- 

 spring, and two or three times a day she used to fly off the nest call- 

 ing on her brood to follow ; but, on hearing their cries of distress 

 from cold, she always returned immediately, and sat with patience for 

 six or seven hours more. I found that it only took the hen one day 

 to learn the meaning of these cries of distress ; for, after the first day, 

 she would always run in an agitated manner to any place where I con- 

 cealed the ferrets, provided that this place was not too far away from 

 the nest to prevent her from hearing their cries. Yet I do not think 

 it would be possible to imagine a greater contrast between two cries 

 than the shrill, piping note of a young chicken and the hoarse, growl- 

 ing noise of a young ferret. At times the hen used to fly off the nest 

 with a loud scream, which was doubtless due to the imaccustomed 

 sensation of being nipped by the young ferrets in their seai'ch for the 

 traditional source of mammalian nutriment. It is further worthy of 

 remark that the hen showed so much anxiety when the ferrets were 

 taken from the nest to be fed, that I adopted the plan of giving them 

 the milk in their nest, and with this arrangement the hen seemed quite 

 satisfied ; at any rate she used to chuck when she saw the milk com- 

 ing, and surveyed the feeding with evident satisfaction. 



Thus we see that even the oldest and most important of instincts in 

 bees and birds admit of being greatly modified, both in the individual 

 and in the race, by intelligent adaptation to changed conditions of life ; 

 and therefore we can scarcely doubt that the principle of lapsing in- 

 telligence must be of much assistance to that of natural selection in 

 the origination and development of instinct. 



*I shall now turn to another branch of the subject. From the 



