This imperfect union of parental constitutions in the constitutions of offspring, is still more clearly illustrated by the re-appearance of peculiarities traceable to bygone generations. Forms, dispositions, and diseases, possessed by distant progenitors, habitually come out from time to time in descendants. Some single feature, or some solitary tendency, will again and again show itself, after being apparently lost. It is notoriously thus with gout, scrofula, {396} and insanity. On some of the monumental brasses in our old churches are engraved heads having traits still persistent in the same families. Wherever, as in portrait galleries, a register of ancestral faces has been kept, the same fact is more or less apparent. The pertinacity with which particular characteristics re-produce themselves is well exemplified in America, where traces of negro blood can be detected in the finger nails, when no longer visible in the complexion. Among breeders of animals it is well known that, after several generations in which no visible modifications were traceable, the effects of a cross will suddenly make their appearance. In all which facts we see the general truth that an organism produced from two organisms constitutionally different, is not a homogeneous mean; but is made up of components, taken in variable ways and proportions from the originals.
In a recent number of the Quarterly Journal of the Agricultural Society were published some facts respecting the mixture of French and English races of sheep, bearing collaterally on this point. Sundry attempts had been made to improve the poor French breeds by our fine English ones. For a long time these attempts failed. The hybrids bore no trace of their English male ancestry; but were as dwarfed and poverty-stricken as their French dams. Eventually the cause of failure was found to lie in the relative heterogeneity and homogeneity of the two constitutions. The superior English sheep were of mixed race; the French sheep, though inferior, were of pure race; and the compound, imperfectly co-ordinated constitution of the one could not maintain itself against the simple and completely balanced constitution of the other. This, at first an hypothesis, was presently demonstrated. French sheep of mixed constitution having been obtained by uniting two of the pure French breeds, it was found that these hybrid French sheep, when united with the English ones, produced a cross in which the English characteristics were duly {397} displayed. Now, this inability of a mixed constitution to stand its ground against an unmixed one, quite accords with the above induction. An unmixed constitution is one in which all the organs are exactly fitted to each other—are perfectly balanced: the system as a whole, is in stable equilibrium. A mixed constitution, on the contrary, being made up of organs belonging to two separate sets, cannot have them in exact fitness—cannot have them perfectly balanced; and a system in comparatively unstable equilibrium results. But in proportion to the stability of the equilibrium will be the power to resist disturbing forces. Hence, when two constitutions, in stable and unstable equilibrium respectively, become disturbing forces to each other, the unstable one will be overthrown, and the stable one will assert itself unchanged.
The imperfect co-ordination of parts in a mixed constitution, and this consequent instability of its equilibrium, are intimately connected with the vexed question of genera, species, and varieties; and, with a view partly to the intrinsic interest of this question, and partly to the further elucidation of the topic in hand, I must again digress.
The current physiological test of distinct species is the production of a non-prolific hybrid. The ability of the offspring to reproduce itself is held to indicate that its parents are of the same species, however widely they may differ in appearance; and its inability to do this is taken as proof that, nearly allied as its parents may seem, they are distinct in kind. Of late, however, facts have been accumulating that tend more and more to throw doubt on this generalization. Cattle-breeders have established it as a general fact, that the offspring of two different breeds of sheep or oxen dwindle away in a few generations if allied with themselves; and that a good result can be obtained only by mixing them with one or other of the original breeds—a fact implying that what is true of so-called species, is, under a modified form, true of varieties also. {398} The same phenomena are observable in the mixtures of different races of men. They, too, it is alleged, cannot maintain themselves as separate varieties; but die out unless there is intermarriage with the originals. In brief, it seems that the hybrids produced from two distinct races of organisms may die out in the first, second, third, fourth, fifth, &c., generation, according as the constitutional difference of the races is greater or less. Now, the experience of the French sheep-breeders, above-quoted, suggests a rationale of these various results. For if it be true that an organism produced by two unlike organisms is not a mean between them, but a mixture of parts of the one with parts of the other—if it be true that these parts belonging to two different sets are of necessity imperfectly co-ordinated; then it becomes manifest that in proportion as the difference between the parent organisms is greater or less, the defects of co-ordination in the offspring will be greater or less. Whence it follows that, according to the degree of organic incongruity between the parents, we may have every gradation in the offspring, from a combination of parts so incongruous that it will not work at all, up to a combination complete enough to subsist permanently as a race. And this is just what we find in fact. Between organisms widely differing in character, no intermediate organism is possible. When the difference is less, a non-prolific hybrid is produced—an organism so ill co-ordinated as to be capable only of incomplete life. When the difference is still less, there results an organism capable of reproducing itself; but not of bequeathing to its offspring complete constitutions. And as the degrees of difference are further diminished, the incompleteness of constitution is longer and longer in making its appearance; until we come to those varieties of the same species which differ so slightly that their offspring are as permanent as themselves. Even in these, however, the organic equilibrium seems less perfect; as is illustrated {399} in the case I have quoted. And in connexion with this inference, it would be interesting to inquire whether pure constitutions are not superior to mixed ones, in their power of maintaining the balance of vital functions under disturbing conditions. Is it not a fact, that the pure breeds are hardier than the mixed ones? Are not the mixed ones, though superior in size, less capable of resisting unfavourable influences—extremes of temperature, bad food, &c.? And is not the like true of mankind?
Returning to the topic in hand, it is manifest that these facts and reasonings serve further to enforce the general truth, that the offspring of two organisms not identical in constitution is a heterogeneous mixture of the two, and not a homogeneous mean between them.
If, then, bearing in mind this truth, we remember the composite character of the civilized races—the mingling in ourselves, for example, of Celt, Saxon, Norman, Dane, with sprinklings of other tribes; if we consider the complications of constitution that have arisen from the unions of these, not in any uniform manner, but with utter irregularity; and if we recollect that the incongruities thus produced pervade the whole nature, mental and bodily—nervous tissue and other tissues; we shall see that there must exist in all of us an imperfect correspondence between parts of the organism that are really related; and that as one manifestation of this, there must be more or less of discrepancy between the features and those parts of the nervous system with which they have a physiological connexion.
If this be so, then the difficulties which stand in the way of the belief that beauty of character is related to beauty of face are considerably diminished. It becomes possible to admit that plainness may co-exist with nobility of nature, and fine features with baseness; and yet to hold that mental and facial perfection are fundamentally connected, and will, when the present causes of incongruity have worked themselves out, be ever found united.
THE ORIGIN AND FUNCTION OF MUSIC.
[First published in Fraser’s Magazine for October 1857.]
When Carlo, standing, chained to his kennel, sees his master in the distance, a slight motion of the tail indicates his but faint hope that he is about to be let out. A much more decided wagging of the tail, passing by-and-by into lateral undulations of the body, follows his master’s nearer approach. When hands are laid on his collar, and he knows that he is really to have an outing, his jumping and wriggling are such that it is by no means easy to loose his fastenings. And when he finds himself actually free, his joy expends itself in bounds, in pirouettes, and in scourings hither and thither at the top of his speed. Puss, too, by erecting her tail, and by every time raising her back to meet the caressing hand of her mistress, similarly expresses her gratification by certain muscular actions; as likewise do the parrot by awkward dancings on his perch, and the canary by hopping and fluttering about his cage with unwonted rapidity. Under emotions of an opposite kind, animals equally display muscular excitement. The enraged lion lashes his sides with his tail, knits his brows, protrudes his claws. The cat sets up her back; the dog retracts his upper lip; the horse throws back his ears. And in the struggles of creatures in pain, we see that a like relation {401} holds between excitement of the muscles and excitement of the nerves of sensation.