INSTINCT AND ACQUISITION. 311 



Though the instincts of animals appear and disappear in such sea- 

 sonable correspondence with their own wants and the wants of their 

 oifspring as to be a standing subject of wonder, they have by no 

 means the fixed and unalterable character by which some would dis- 

 tinguish them from the higher faculties of the human race. They vary 

 in the individuals as does their physical structure. Animals can learn 

 what they did not know by instinct and forget the instinctive knowl- 

 edge which they never learned, while their instincts will often ac- 

 commodate themselves to considerable changes in the order of exter- 

 nal events. Everybody knows it to be a common j^ractice to hatch 

 ducks'-eggs under the common hen, thou";h in such cases the hen has 

 to sit a week longer than on her own eggs. I tried an experiment to 

 ascertain how far the time of sitting could be interfered with in the 

 opposite direction. Two hens became broody on the same day, and I 

 set them on dummies. On the third day I put two chicks a day old 

 to one of the hens. She pecked at them once or twice; seemed rather 

 fidgety, then took to them, called them to her and entered on all the 

 cares of a mother. The other hen was similarly tried, but with a 

 very difierent result. She pecked at the chickens viciously, and both 

 that day and the next stubbornly refused to have any thing to do with 

 them. 



The i3ig is an animal that has its wits about it quite as soon after 

 birth as the chicken. I therefore selected it as (i subject of observa- 

 tion. The following are some of my observations: That vigorous 

 young pigs get xip and search for the teat at once, or within one min- 

 ute after their entrance into the world. That if removed several feet 

 from their mother, when aged only a few minutes, they soon find their 

 way back to her, guided aj^parently by the grunting she makes in an- 

 swer to their squeaking. In the case I observed the old sow rose in less 

 than an hour and a half after pigging, and went out to eat ; the pigs 

 ran about, tried to eat various matters, followed their mother out, and 

 sucked while she stood eating. One pig I put in a bag the moment it 

 was born and kept it in the dark until it was seven hours old, when I 

 placed it outside the sty, a distance of ten feet from where the sow 

 lay concealed inside the house. The pig soon recognized the low 

 grunting of its mother, went along outside the sty struggling to get 

 under or over the lower bar. At the end of five minutes it succeeded 

 in forcing itself through under the bar at one of the few places where 

 that was possible. No sooner in than it went Avithout a pause into the 

 pig-house to its mother, and was at once like the others in its behavior. 

 Two little pigs I blindfolded at their birth. One of them I placed 

 with its mother at once: it soon found the teat and began to suck. 

 Six hours later I placed the other a little distance from the sow ; it 

 reached her in half a minute, after going about rather vaguely; in 

 half a minute more it found the teat. Next day I found that one of 

 the two left with the mother, blindfolded, had got the blinders ofi"; the 



