INSTINCTS. 
177 
nor the mother, but by the neutral bee. Probably the case 
is the same with ants. , 
1 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 con¬ 
vex surface of the shells against the abdomen, or by the 
relief which the mild temperature of the egg may afford 
to the heat of the lower part of the body, which is observ¬ 
ed 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 accidental consequence. The affection 
of viviparous animals for their young is, in like manner, 
solved by the relief, and perhaps the pleasure, which they 
receive from giving suck. The young animal’s seeking, 
in so many instances, the teat of its dam, is explained from 
the sense of smell, which is attracted by the odour of 
milk. The salmon’s urging its way up the stream of fresh 
water rivers, is attributed to some gratification or refresh¬ 
ment, 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 lamb, appear to be prior to their sucking. The at¬ 
traction of the calf or lamb to the teat of the dam, is not 
explained by simply referring it to the sense of smell. 
What 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 which it proceeded? No observation, 
no experience, no argument could teach the new dropped 
animal, that the substance from which the scent issued, 
was the material of its food. It had never tasted milk be¬ 
fore its birth. None of the animals, which are not de¬ 
signed for that nourishment, ever offer to suck, or to seek 
Dut any such food. What is the conclusion, but that the 
sugescent parts of animals are fitted for their use, and 
the knowledge of that use put into them? 
