September 5, 1901] 



NA TURE 



461 



and to measure distance with something like infaUible accurac)-. 

 A chicken was unhooded when nearly three days old. For six 

 minutes it sat chirping and looking about it ; at the end of that 

 time it followed with its head and eyes the movements of a fly 

 twelve inches distant, at twelve minutes it made a peck at its 

 own toes, and the next instant it made a vigorous dart at the 

 fly, which had come within reach of its neck, and seized and 

 swallowed it at the first stroke ; for seven minutes more it sat 

 calling and looking about it. For about thirty minutes more 

 it sat on the spot where its eyes had been unveiled without 

 attempting to walk a step. It was then placed on rough ground 

 within sight and call of a hen with a brood of about its own age. 

 After standing chirping for about a minute, it started off towards 

 the hen, displaying as keen a perception of the qualities of the 

 outer world as it was ever likely to possess in after life. It 

 never required to knock its head against a stone to discover that 

 there was no road there. It leaped over the smaller obstacles 

 that lay in its path and ran round the larger, reaching the mother 

 in as straight a line as the nature of the ground would permit. 

 This, let it be remembered, was the first time it had ever 

 walked by sight." 



In this experiment each movement of the chicken appears to 

 have been started by an external stimulus. It pecked at the 

 flies which it saw. It jumped or evaded the objects which it 

 saw in its path. It remained stationary until its hereditary 

 tendencies were stimulated, by the sound and sight of the old 

 hen in its neighbourhood. 



Mr. Spalding again says : — "The art of scraping in search of 

 food, which, if anything, might be acquired by imitation, is never- 

 theless another indubitable instinct. Without any opportunities 

 of imitation, when kept quite isolated from their kind, chickens 

 began to scrape when from two to six days old. Generally the 

 condition of the ground was suggestive, but I have several times 

 seen the first attempt, which consisted of a sort of nervous 

 dance, made on a smooth table." Mr. Spalding, however, does 

 not seem to have seen them scrape unless the ground was sug- 

 gestive, and Dr. Allen Thompson hatched out some chickens on 

 a carpet where he kept them for several days. They showed no 

 inclination to scrape because the stimulus applied to their feet 

 was of too novel a character to call into action their hereditary 

 instinct ; but when Dr. Thompson sprinkled a little gravel on 

 the carpet and so supplied the appropriate or customary stimulus, 

 the chickens immediately began their scraping movements. Here, 

 again, we see the hereditary instinct requiring a local stimulus to 

 bring it about. 



Mr. Spalding again says : — " A young turkey, which I had 

 adopted when chirping within the uncracked shell, was on the 

 morning of the tenth day of its life eating a comfortable break- 

 fast from my hand, when the young hawk in a cupboard ust 

 behind us gave a shrill chip, chip, chip. Like an arrow the 

 poor turkey shot to the other side of the room, stood there 

 motionless and dumb with fear, until the hawk gave a second 

 cry, when it darted out at the open door right to the extreme 

 end of the passage, and there, silent and crouched in a corner, 

 remained for ten minutes. Several times during the course of 

 that day it again heard these alarming sounds, and in every 

 instance with similar manifestations of fear." Generations of 

 young turkeys must in their native home have had cause to 

 dread the cry of birds of prey ; and the hereditary lesson had 

 been well learned. 



A water-bird was reared from the egg by another observer. 

 It would swim freely, but he could not get it to dive by any 

 means which he tried. One day while watching it in the water, 

 a dog suddenly appeared on the bank. The necessary stimulus 

 was applied ; the hereditary reflex was set in action, and in the 

 twinkling of an eye the bird had dived. 



Handed down from generation to generation as these instincts 

 have been, and impressed upon their owners by the imperative 

 law that failure to inherit an instinct or a reflex meant death to 

 the degenerate, these reactions persist long after they have failed 

 to be of use. 



As Dr. Louis Robinson has pointed out, the horse roamed, in 

 a wild state, over plains of more or less long grass and low 

 bushes. When a horse is alarmed, he throws up his head to get 

 as wide a view as possible. The cow on the other hand keeps 

 her head low, as if to peer under the boughs which covered 

 the marshy grass of her jungle home. The horse's chief danger 

 lay when, as he approached a stream to drink, he was liable to 

 be sprung upon by a lurking lion ; and to this day the two things 

 that a horse dreads most are the rustling in bushes or reeds 



by the road-side and the wheelbarrow or tree-stump which his 

 imagination depicts as a crouching enemy. 



The dog once formed his lair in rough stuff, and now, when 

 approaching sleep gives the accustomed stimulus, our pet dogs 

 turn round three times upon the hearthrug to smooth down 

 imaginary grass stubs. As an instance of an instinct which by 

 its persistence under altered circumstances has become actually 

 prejudicial, I may give the case of some shore-birds which had 

 for many years nested upon flats covered with pebbles. As long 

 as the pebbles remained, the eggs, which closely resembled them 

 in markings, were rendered inconspicuous, but as the sea receded 

 and grass grew, the pebbles became few and far between. The 

 birds still, however, kept to their haunt, and actually collected 

 pebbles around their eggs, thereby rendering their nests the 

 more conspicuous. 



In domestic fowls the habit of cackling as soon as they have 

 laid an egg would certainly be detrimental to a wild race, and 

 Hudson makes some interesting remarks on the modified habit 

 in a semiferal race. The CreoUa fowls, descended through three 

 hundred years from the fowls introduced by the early settlers in 

 La Plata, are much persecuted by foxes, skunks, ^c, ever on 

 the look-out for their eggs or themselves. These fowls in 

 summer always lived in small parties, each party composed of 

 one cock and as many hens as he could collect — usually three or 

 four. Each family occupied its own feeding-ground, where it 

 would pass a greater portion of each day. The hen would nest 

 at a considerable distance from the feeding-ground, sometimes 

 as far as four or five hundred yards away. 



After laying an egg she would quit the nest, not walking from 

 it as other fowls do, but flying, the flight extending to a distance 

 of from fifteen to about fifty yards ; after which, still keeping 

 silence, she would walk or run, until, arrived at the feeding- 

 ground, she would begin to cackle. At once the cock, if within 

 hearing, would utter a responsive cackle, whereupon she would 

 run to him and cackle no more. Frequently the cackling call- 

 note would not be uttered more than two or three times, some- 

 times only once, and in a much low'er tone than in fowls of other- 

 breeds. If we may assume that these fowls in their long semi- 

 independent existence in La Plata have reverted to the original 

 instincts of the wild Callus bankiva, we can see how advan- 

 tageous the cackling instinct must be in enabling the hen ia 

 dense tropical jungles to rejoin the flock after laying an egg, 

 while if there are egg-eating animals in the jungle intelligent 

 enough to discover the meaning of such a short subdued cackle, 

 they would still be unable to find the nest by going back on the 

 bird's scent, since she flies from the nest in the first place ! It 

 is obvious that while this form of cackling is useful, excessive 

 cackling would in a state of nature lead to its own suppression. 



We may suppose that as the wild fowl became more and more 

 closely domesticated the eggs of the greater cacklers were more 

 rapidly found and preserved by their mistresses, and this tended 

 to increase the tendency to cackle ; while in the half-wild fowls 

 of settlers who had plenty to do besides looking after their 

 poultry, there was a gradual reversion to the wild type by the 

 elimination of the eggs of loud cacklers when net rapidly re- 

 trieved. 



Birds which nest within a short distance of the ground display, 

 as a rule, great skill in concealing their nests, and are very con- 

 servative in type. How is it that one chaffinch's nest is so like 

 another's ? 



Gregarious birds like rooks have opportunities for learning by 

 imitation, and may thus have lost some of their spontaneous- 

 skill. I have read somewhere that, when rooks were introduced 

 into the Antipodes, young birds having been selected for trans- 

 portation, they were found, when the breeding season came> 

 round, to be at fault, and finally imitated the nest of some- 

 native bird ; but chaffinches build apart from one another ; how, 

 then, do they get their nests so nearly alike ? A great observer 

 has suggested that this is due to recollection on the part of the 

 nesting pair of the home in which they were reared. This ex- 

 planation does not commend itself to my mind, and is refuted, 

 if not by the instance of the rooks just quoted, by the fact that 

 tame canaries hatched in a nest of felt will, when they them, 

 selves breed, use moss for the foundation of their nest, and hair 

 as a lining, just as a wild bird would do, although, as they build 

 in a box, the hair alone would be sufficient. 



If you want examples of what pure instinct can do, go to the 

 insect world. There you get them in infinite variety. Hatched 

 from the egg long after the death of the mother, the majority 

 of insects have to depend entirely on the duly ordered reaction 



NO. 1662, VOL. 64] 



