mitted by heredity. But, unfortunately, we can study them only under the specific form. There, however, there is no room for doubt, for heredity transmits them all without exception.

In the human species, savage races have a characteristic acuteness of smell which allies them to animals. In North America the Indians can follow their enemies or their game by the scent, and in the Antilles the maroon negroes distinguish by the scent a white man's trail from a negro's.1 The whole negro race has this sense developed to an extraordinary degree. Whether this results from a great development of the olfactive membrane, or from the more frequent exercise of this sense, in any case, this innate or acquired faculty is preserved by heredity, The specific and individual varieties of taste are transmissible, like those of smell. Hybridism gives curious examples of this among animals. 'The swine,' says Burdach, 'has a very strong liking for barley; the wild boar will not touch it, feeding on herbage and leaves. From a cross between a domestic sow and a wild boar come young some of which have an aversion for barley, like the wild boar, while the others have a taste for it, like the common hog.'

In man, anæsthesia of taste, and antipathy for certain flavours, are hereditary. Schook, the author of a treatise entitled De Aversione Casei belonged to a family to nearly all the members of which the smell of cheese was unendurable, and some of whom were thrown into convulsions by it.2 Such antipathy is very often hereditary. In a family of our acquaintance, the father and mother like cheese; the grandmother had an extreme dislike for it. Four of the children share in the same dislike.'3

An exclusive liking for vegetable food and repugnance to flesh is of very rare occurrence, but it is transmissible. 'A soldier of the Engineers, who derived from his father an invincible repugnance to all food composed of animal substances, was unable, during the 18 months he spent with his regiment, to overcome this aversion, and was obliged to quit the service.'4

Finally, P. Lucas, following Zimmermann and Gall, gives the

1 Dictionnaire des Sciences Médicales. 3 Lucas, i. 389.

Art. 'Odorat.'

2 Ibid.

4 Gazette des Tribunaux, 21 Mai, 1844.

following surprising case. A Scotchman had an irresistible longing for human flesh, which led him to commit several murders. He had a daughter, who, though taken from her parents, who were burned at the stake, before she was a year old, and though she was brought up among respectable people, still succumbed, like her father, to the inconceivable desire for eating human flesh.1

There exists in some families a sort of natural hydrophobia. 'Three members of a family with which we are acquainted—the grandmother, the mother, and a daughter-eat their food without taking any liquid; they do not drink at all, we might say. Their repugnance to liquids is so great that they refuse to drink until they fall into a feverish state.'

3

We have collected sufficient facts enough to show that there is such a thing as heredity of the perceptive faculties, even under the individual form. Thus, if we take an animal, as it is naturally constituted, with its sensorial organs, through which it comes in contact with the outer world, we may say that the quantity and quality of its perceptive, faculties will be certainly transmitted in their specific form, and very probably too in their individual form; therefore, heredity is the rule.

Sensation, however, presents only the raw material of cognition, which the mind's own activity has to transform and elaborate. To the external element supplied by the material world must be added the internal element supplied by ourselves, in order to produce what is properly called cognition, and the development of the mind. Hence it might be said that the heredity of the perceptive faculties, as here considered, is in some manner external, and that our having established it is a physiological rather than a psychological result. In our opinion, however, this is not the case, nor would that objection be made if it were borne in mind that per

1 We state this case with great reserve, because its authenticity does not appear to be beyond question. It is not, however, more improbable than other cases of heredity. It is notorious that the inclination to cannibalism is extremely lasting. A New Zealander of great intelligence, half-civilized by a protracted sojourn in England, while admitting that it was wrong to eat a fellow-man, still longed for the time to come when he could have that pleasure. Lucas, i. p. 391.

2 Lucas, ibid. 388.

ception is an act essentially active, into which the whole mind enters. But we need not dwell upon a point which would require a lengthy explanation, carrying us beyond the limits of our subject. We shall presently see whether the heredity of the intellectual faculties, in their highest forms, can be directly established.

CHAPTER III.

HEREDITY OF THE MEMORY.

I.

IF, in treating of Memory, we confine ourselves to a description of the phenomena, and the investigation of their organic conditions, our task is simple. Nothing is easier than to attribute recollection to a special faculty which knows the past as consciousness knows the present. Unfortunately, however, this supposed faculty adds nothing to our knowledge, and with it we are in possession of only what the phenomena gave us, with just a word over. On the other hand, when we go beyond mere description and verbal explanations, the problem of memory, simple as it appears, becomes very difficult. Yet since, in order to understand the relation between heredity and memory, it is necessary to have some precise notions about this subject, the problem must be attempted.

The phenomena of memory, considered in their ultima ratio, are explained by the law of the indestructibility of force, of the conservation of energy, which is one of the most important laws of the universe. Nothing is lost; nothing that exists can ever cease to be. In physics, this is admitted readily enough; the principle is well-established, and confirmed by so many facts, that doubt is impossible. In morals, the case is different: we are commonly so accustomed to regard all occurrences as the results of chance, and as subject to no laws, that many at least implicitly admit the annihilation of that which once was a state of consciousness to be possible. Yet annihilation is as inadmissible in the moral as it is in the physical world; and but little reflection is needed to see that in all orders of phenomena it is alike impossible for something to become nothing, or for nothing to become something. Such a

miracle is neither conceived by reason nor justified by experience. We may, indeed, state such a proposition verbally; but so soon as we pass from words to things, from vagueness to precision, from the imaginary to the real, we cannot form an idea of any such annihilation in external or internal experience.

Nor are the considerations in favour of the indestructibility of our perceptions and ideas merely of a theoretical nature; there are also facts which, however strange they may appear at first, are very simple, if we bear in mind that in the mental world, as elsewhere, nothing perishes. Works on medicine and psychology cite numerous instances where languages apparently altogether forgotten, or memories apparently effaced, are suddenly brought back to consciousness by a nervous disorder, by fever, opium, hasheesh, or simply by intoxication. Coleridge tells a story of a servant-maid, who, in a fever, spoke Greek, Hebrew, and Latin; Erasmus mentions an Italian who spoke German, though he had forgotten that language for twenty years; there is also a case recorded of a butcher's boy who, when insane, recited passages from the Phedre which he had heard only once. All these facts are so well known that they need only here be cited; they, with many others, prove that in the depths of the soul there exists many a memory which seemed to have vanished for ever.

The physiological study of perception further shows that the production of the phenomena of consciousness is subject to the law of the transformation of force. Though this point is yet beset with difficulties, the works of Mateucci and of Dubois-Reymond show that electric currents are produced in the nerves, and are there in continual circulation. When sensation takes place, and in general whenever a nerve is active, there is produced a diminution of its special current, as is indicated by the needle of a galvanometer connected with the nerve. This diminution takes place because a molecular change is produced within the nerve, which, on reaching the muscles, produces a contraction, and on reaching the brain produces a sensation;-in other words, sensation is work, and to perform work a certain force has to be expended and transformed. The electrical forces which serve to produce the sensation could not, at the same time, either give motion to a magnetic needle or produce chemical decomposition, because, while per

forming work within they cannot, at the same time, perform work without; and 'as the nerve cannot produce electricity without using up something, the ultimate source of the forces which the nerve transforms into electricity is the materials furnished by the blood. The nerve is nourished with these materials, as the pile is fed with zinc and acid.'1 Thus perception-that is to say, the primary phenomena of consciousness-comes under the general law. It is impossible that it should come of nothing. We daily experience thousands of perceptions, but none of these, however vague and insignificant, can perish utterly. After thirty years some effort-some chance occurrence, some malady—may bring them back; it may even be without recognition. Every experience we have had lies dormant within us: the human soul is like a deep and sombre lake, of which light reveals only the surface; beneath, there lives a whole world of animals and plants, which a storm or an earthquake may suddenly bring to light before the astonished consciousness.

Both theory and fact, then, agree in showing that in the moral, no less than in the physical world, nothing is lost. An impression made on the nervous system occasions a permanent change in the cerebral structure, and produces a like effect in the mind-whatever may be understood by that term. A nervous impression is no momentary phenomenon that appears and disappears, but rather a fact which leaves behind it a lasting result-something added to previous experience and attaching to it ever afterwards. Not, however, that the perception exists continually in the consciousness ; but it does continue to exist in the mind, in such a manner that it may be recalled to the consciousness.

It is not easy to say what it is that survives our perceptions and ideas. The least objectionable name for it is residuum, a term which does not imply any theory, because it only indicates an unquestionable fact of our mental life. It is not to be supposed that these residua are always present to the mind, so that the attention can at any moment be voluntarily directed to them. But it may be assumed that every mental act leaves in our physical and mental structure a tendency to reproduce itself, and that when

1 Wundt, Menschen- und Thierseele, 5th and 6th Lectures.