ON INSTINCT. 



213 



Habit, imitation, and instruction would all concur in teaching them to flee 

 from the water, as a source of inevitable destruction : and yet, in opposition 

 to all these influences and premonitions, we see them rush into it, and harm- 

 lessly: we see them obeying an irresistible impulse, which directs them to 

 what is fitting, stamped in the interior of their little frames, and which is 

 equally remote from the laws of mind and of mechanism. 



In like manner, by what process of imitation, education, or reasoning does 

 the nut-weevil (curculio nucum) seek out exclusively, and with the nicest 

 knowledge of the plant, the green hazel in the month of August, while its 

 nut-shell is yet soft and easily penetrable 1 What past experience or course 

 of argument instructs her that this is the fruit best adapted, or perhaps only 

 adapted, to the digestive powers of her future progeny ? With a finished 

 knowledge of her art, as soon as she is prepared to deposite her eggs, she 

 singles out a nut, pierces it with her proboscis, and then, turning round ac- 

 curately, drops an egg into the minute perforation ; having accomplished 

 which, she passes on, pierces another nut, drops another egg, and so con- 

 tinues till she has exhausted her entire stock. The nut, not essentially in- 

 jured, continues to grow. The egg is soon hatched; the young larve or 

 maggot finds its food already ripened and in waiting for it ; and about the tirme 

 of its full growth, falls with the mature nut to the ground, and at length 

 creeps out by gnawing a circular hole in the side. It then burrows under the 

 surface of the ground, where it continues dormant for eight months, at the 

 termination of which time it casts its skin, commences a chrysalis of the 

 general shape and appearance of the beetle kind, and in the beginning of 

 August throws off the chrysalid investment, creeps to the surface of the 

 ground, finds itself accommodated with wings, becomes an inhabitant of the 

 air, and instantly pursues the very same train of actions to provide for a new 

 progeny which had been pursued by the parent insect of the year before. 



In all such cases it is clear that there is a principle implanted in the living 

 form equally distinct from all mechanical, chemical, and rational powers, 

 which directs the agent by an unerring impulse, or, in other words, impels it 

 by a prescribed and unerring law, to accomplish a definite end by a definite 

 means. 



Such instinctive powers are not only allowed upon Mr. Smellie's hypo- 

 thesis, but are conceived to be almost innumerable ; and reason, instead of 

 giving birth to them, is, in his opinion, as I have already observed, the general 

 result of them, and consists in the power of comparing one instinct with 

 another, and assenting to those that preponderate. According to this hypo- 

 thesis, all the actions of the involuntary organs of the body are so many in- 

 stincts, as pulsation, digestion, secretion ; all natural feelings are so many 

 instincts, as lo'^e of life, dread of death, and the desire of progeny; all the 

 passions are so many instincts, as fear, hope, envy, benevolence, reverence, 

 superstition, devotion ; and hence life is nothing more than a bundle of in- 

 stincts ;* and reason, which is itself founded upon an instinctive principle, 

 consists, as I have just observed, of nothing more than a power or tendency 

 to compare the different strengths of these antagonist forces whenever they 

 are brought into a state of action, and to be guided by those that are prepol- 

 lent ; or that offer what is felt or conceived to be the best means of obtaining 

 a proposed end. The objections to which this hypothesis is exposed, or 

 rather the evils chargeable upon it, are innumerable ; but it is sufficient to ob- 

 serve, at present, that it as effectually confounds the separate faculties of 

 instinct and reason as the preceding hypothesis of Dr. Darwin, and, conse- 

 quently, that neither of the two opinions are in any respect more admissible 

 than those which refer the instinctive faculty to a mechanical principle, or, 

 in other words, to the common properties of unorganized matter. 



III. There is a third class of philosophers, who, sensible of the difliculty 

 of the case, have endeavoured to get over it by contending that instincts are 

 of a mixed kind : that they either originate in a power which holds an inter* 



* Transact of the Royal Society of Edinb. vol. v. p. 39. 



