reptiles. Nevertheless, a bat was all the while a mammal, and a pterodactyl was not a bird; and it admits of proof as definite, that what we call instinct in animals occurs in man, and that what we call reason in man occurs in animals. This, I mean, is the case if we wait to attach any definition to the words which we employ. It is quite evident that there is some difference between the mind of a man and the mind of a brute, and if, without waiting to ascertain what this difference is, we say that it consists in the presence or absence of the faculty of reason, we are making the same kind of mistake as when we say that the difference between a bird and a mammal consists in the presence or absence of the faculty of flying. Of course, if we choose, we may employ the word "reason" to signify all the differences taken together, whatever they may be; and so, if we like, we may use the word "flying." But in either case we should be talking nonsense, because we should be divesting the words of their meaning, or proper sense. The meaning of the word "reason" is the faculty of ratiocination—the faculty of drawing inferences from a perceived equivalency of relations, no matter whether the relations involve the simplest mental perceptions, or the most abstruse mathematical calculations. And in this, the only real and proper sense of the word, reason is not the special prerogative of man, but occurs through the zoölogical scale at least as far down as the articulata.
What, then, is to be our definition of instinct?
First of all, instinct involves mental operation, and therefore implies consciousness. This is the point which distinguishes instinct from reflex action. Unless we assume that a new-born infant, for example, is conscious of sucking, it is as great a misnomer to term its adaptive movements in the performance of this act instinctive as it would be similarly to term the adaptive movements of its stomach subsequently performing the act of digestion.
Next, instinct implies hereditary knowledge of the objects and relations with respect to which it is exercised; it may therefore operate in full perfection prior to any experience on the part of the individual. When the pupa of a bee, for instance, changes into an imago, it passes suddenly from one set of experiences to another—the difference between its previous life as a larva and its new life as an imago being as great as the difference between the lives of two animals belonging to two different sub-kingdoms; yet as soon as its wings are dry it exhibits all the complex instincts of the mature insect in full perfection. And the same is true of the instincts of vertebrated animals, as we know from the researches of the late Mr. Douglas Spalding and others.
Again, instinct does not imply any necessary knowledge of the relation between means employed and ends attained. Such knowledge may be present in any degree of distinctness, or it may not be present at all; but in any case it is immaterial to the exercise of the instinct. Take, for example, the instinct of the Bembex. This insect brings
