INSTINCTS. 207 



grub is nurtureJ neither by the father nor the mother, but by 

 the neutral bee. Probably the case is the same with ants. 



I am not ignorant of the theory which resolves instinct 

 into sensation, which asserts that what appears to have a 

 view and relation to the future, is the result only of the 

 present disposition of the animal's body, and of pleasure or 

 pain experienced at the time. Thus the incubation of eggs 

 is accounted for by the pleasure which the bird is supposed 

 to receive from the pressure of the smooth convex surface o( 

 the shells against the abdomen, or by the relief which the 

 mild temperature of the egg may aflbrd to the heat of the 

 lower part of the body, which is observed at this time to be 

 increased beyond its usual state. This present gratification 

 is the only motive with the hen for sitting upon her nest ; 

 the hatching of the chickens is, with respect to her, an acci- 

 dental consequence. The affection of viviparous animals for 

 their young is in like manner solved by the relief, and per- 

 haps the pleasure, which they perceive from giving suck. 

 The young animal's seeking, in so many instances, the teat 

 of its dam, is explained from its sense of smell, which is 

 attracted by the odor of milk. The salmon's urging its w^ay 

 up the stream of fresh-water rivers, is attributed to some 

 gratification or refreshment which, in this particular state of 

 the fish's body, she receives from the change of element. 

 Now of this theory it may be said, 



First, that of the cases which require solution, there are 

 few^ to which it can be applied with tolerable probability ; 

 that there are none to which it can be applied without 

 strong objections, furnished by the circumstances of the case. 

 The attention of the cow to its calf, and of the ewe to its 

 Limb, appear to be prior to their sucking. The attraction 

 of the calf or lamb to the teat of the dam, is not explained by 

 lUinply referring it to the sense of smell. "VYhat made the scent 

 of milk so agreeable to the lamb that it should follow it up 

 with its nose, or seek with its mouth the place from wliich 

 it proceeded ? No observation, no experience, no argument 



