The sexes of canines don’t differ, except that in sure breeds, especially within the Scotch deer-hound, the male is far larger and heavier than the female; and, as we shall see in a future chapter, the male goes on growing in size to an unusually late interval of life, which, in response to rule, will account for his increased dimension being transmitted to his male offspring alone. Now we have as but thought-about the transference of characters, relatively to their period of improvement, only in species in a natural state; we are going to now flip to domesticated animals, and first touch on monstrosities and diseases. We have cases of this reality in all black and white breeds, through which the young and old of each sexes are alike; nor can or not it’s maintained that there is one thing peculiar in a black or white plumage, which ends up in its transference to each sexes; for the males alone of many natural species are either black or white, the females being otherwise coloured. The very same character, similar to deficient or supernumerary digits, colour-blindness, &c., might with mankind be inherited by the males alone of one family, and in one other household by the females alone, though in both instances transmitted by the alternative in addition to through the same sex.

In the same method, if any variation appeared in a feminine pigeon, which was from the primary sexually limited in its improvement to the females, it would be simple to make a breed with the females alone thus characterised; but if the variation was not thus initially restricted, the process would be extraordinarily tough, maybe not possible. Then again, in many of the breeds during which the two sexes resemble one another, the young are colored in almost the same method as their mother and father, and this renders it probable that their colours first appeared early in life. With the so-called Cuckoo sub-breeds of the fowl, through which the feathers are transversely pencilled with dark stripes, both sexes and the chickens are coloured in practically the identical method. I used to be first led to infer that a relation of this kind exists, from the fact that at any time when and in whatever manner the grownup male differs from the adult female, he differs in the identical manner from the young of both sexes.

When, then again, the adult male intently resembles the younger of both sexes (these, with rare exceptions, being alike), he typically resembles the adult feminine; and in most of these instances the variations via which the younger and outdated acquired their current characters, probably occurred, in response to our rule, throughout youth. In all these instances the variations, by means of the accumulation of which the male acquired his correct masculine characters, must have occurred at a somewhat late interval of life; in any other case the young males would have been equally characterised; and conformably with our rule, the variations are transmitted to and developed in the adult males alone. Thus in all the numerous breeds wherein the grownup male differs significantly in color from the female, in addition to from the wild mum or dad-species, he differs additionally from the young male, in order that the newly-acquired characters must have appeared at a reasonably late interval of life. The presence of supernumerary digits, and the absence of certain phalanges, have to be decided at an early embryonic interval-the tendency to profuse bleeding is no less than congenital, as might be color-blindness-but these peculiarities, and other related ones, are often restricted of their transmission to 1 sex; so that the rule that characters, developed at an early interval, tend to be transmitted to each sexes, right here wholly fails.

But with domesticated sheep the presence or absence of horns isn’t a firmly fastened character; for a certain proportion of the merino ewes bear small horns, and a few of the rams are hornless; and in most breeds hornless ewes are occasionally produced. Now in seven species, belonging to distinct sections of the household and inhabiting completely different regions, by which the stags alone bear horns, I discover that the horns first appear at periods, various from nine months after beginning within the roebuck to 10, twelve or even more months in the stags of the six other and bigger species. In a number of sorts of antelopes, only the males are supplied with horns, while in the higher quantity both sexes bear horns. In all the species, however one, the horns are developed only in the males, though certainly transmitted by way of the females, and capable of abnormal growth in them. The male and female Peacock differ conspicuously from one another in nearly every part of their plumage, besides in the elegant head-crest, which is widespread to both sexes; and that is developed very early in life, lengthy before the other ornaments, that are confined to the male. Alternatively, after this power has been gained and the sexes have come to differ in structure, the gemmules (if I might once more use the language of pangenesis) which are forged off from every varying part within the one intercourse can be more likely to possess the correct affinities for uniting with the tissues of the identical sex, and thus changing into developed, than with these of the opposite sex.