I do not propose to consider particular instances of intelligent inferences as displayed by the invertebrates. Bees in the manipulation of their comb, ants in the economy of their nest, spiders in the construction of their web and the use they make of their silken ropes, show powers of intelligent adaptation which cannot fail to excite our wonder and admiration. But apart from the fact that insect psychology is more largely conjectural than that of the more intelligent mammals, a consideration of these actions would only lead me to reiterate the opinion above frequently expressed. In a word, I regard the bees in their cells, the ants in their nests, the spiders in their webs, as workers of keen perceptions and a high order of practical intelligence. But I do not, as at present advised, believe that they reason upon the phenomena they deal with so cleverly. Intelligent they are; but not rational. Once more, let me repeat that the sense in which I use the words "rational" and "reason" must be clearly understood and steadily borne in mind. Mr. Romanes uses them in a different sense. "Reason," he says,[HE] "is the faculty which is concerned in the intentional adaptation of means to ends. It therefore implies the conscious knowledge of the relation between means employed and ends attained, and may be exercised in adaptation to circumstances novel alike to the experience of the individual and to that of the species. In other words, it implies the power of perceiving analogies or ratios, and is in this sense equivalent to the term 'ratiocination,' or the faculty of deducing inferences from a perceived equivalency of relations. This latter is the only sense of the word that is strictly legitimate." It is not my intention to criticize this use of the term "reason." Whether animals are capable of a conscious knowledge of the relation between means employed and ends attained, depends, as we have already seen, upon how much is implied by the word "knowledge"--whether the knowledge is perceptual or conceptual. My only care is to indicate what seem to me the advantages of the usage (legitimate or illegitimate) I adopt. I repeat, then, that the introduction of the process of analysis appears to me to constitute a new departure in psychological evolution; that the process differs generically from the process of perceptual construction on which it is grafted. And I hold that, this being so, we should mark the departure in every way that we can. I mark it by a restriction of the word "intelligence" to the inferences formed in the field of perception; and the use of the word "reason" when conceptual analysis supervenes. Whether I am justified in so doing, whether my usage is legitimate or not, I must leave others to decide. But, adopting this usage, I see no grounds for believing that the conduct of animals, wonderfully intelligent as it is, is, in any instances known to me, rational.