The frequency of the catanwnial Aix, and the epoch of life to which it extends, appear from Mr. Roberton's inquiries, to be no less constant among different races. It is quite true that the period of child-bearing is sooner terminated among the women of many tribes, especially in tropical climates, than it usually is in this country ; but this is fairly attri butable to the earlier marriages, and the con sequently premature excitement of the gene rative power, of which its earlier decline is the natural consequence. The same is continually seen in this country. The marked difference in this respect, that arises out of laws and customs affecting the marriage state, is shown by the fact, that in India the mean age for a first parturition is 151 years, whilst among 500 Manchester female operatives, tabulated by Mr. Roberton, the mean age was found to be 23 years. Some very curious evidence has been collected by that gentleman, which goes to prove that marriages nearly as pre mature as those of Hindoo females were for merly sanctioned by law and public opinion in this country; and that in Ireland they have been by no means unfrequent within a recent period.
The duration of pregnancy is well known to be the same throughout all the races of man kind ; and this is a fact of peculiar importance, as a difference in this respect is elsewhere observable between species that are in other respects closely allied.
The fertility of hybrid races, originating in the intermixture of two races whose affinity is most remote, is a fact of which there can be no doubt whatever ; and there is strong reason to believe that those hybrid races, the parents of which are Europeans on one side, and the aborigines of any country on the other, are generally destined to become the dominant population of those countries. For, on the one hand, these " half-castes " very commonly combine the best attributes of the two races from whose admixture they sprang; namely, the intelligence and mental activity of the European, and the climatic adaptation of the native.* And they are also in general distinguished for their fertility, when paired with each other, so that they are rapidly rising into numerical importance. On the other hand, this very intermixture, taking place as it usually does between an European father and a native mother, tends to di minish the number of the native population in a very remarkable manner ; for there is now a large amount of evidence, that when a native female of the American or Polynesian races has once been impregnated by an European male, she thenceforth loses all power of conception from intercourse with the male of her own race. This was first pointedly stated by that very intelligent tra veller, the Count de Strzclecki, who has lived much among different races of abo rigines, the natives of Canada, of the United States, of California, Mexico, the South American Republics, the Marquesas, Sand wich, and Society Islands, New Zealand, and Australia, and who affirms that in hundreds of cases of this kind into which he has inquired, and of which he preserves memoranda, there has not been a single exception.*
As regards Australia and New Zealand, this statement, strange as it seems at first sight, has been fully borne out by independent evidence ; and it offers the most complete explanation yet given, of the very rapid de crease in the native population of the various islands of Oceania, in which European races have been long established. Nothing pre cisely analogous is known in any other case. Instances of the influence of the father of a first offspring upon subsequent off spring by another father, are so frequent, as to have given rise to a current be lief among the breeders of domesticated animals, that such is the fact ; and the very ingenious hypothesis has been suggested by Mr. M'Gillivray, and ably advocated by Dr. Harvey, that the female parent in such a case becomes inoculated with the qualities of the male, through the blood of the foetus, which partakes of the latter. But there is no known case, in which impregnation of a female by a male of a different species or variety has ren dered her subsequently infertile to males of her own ; on the contrary, the facts just re ferred to, as to the extension of the influence of the first father over the subsequent progeny, indicate that such is not the case. Hence this peculiarity affords no ground whatever for the establishment of a specific distinction between the two races ; and the invalidity of such a distinction is at once indicated by the fact, that the peculiarity in question does not hold good in regard to the African races, the fertility of the Negro female with the male of her own race not being apparently impaired by 'previous fruitful intercourse with the European male, a kind of intercourse which is notoriously common in the West India Islands, and in the slave-holding states of North and South America.t The Psychical comparison of the various races of mankind is really, in a practical point of view, the most important department of the whole investigation ; and yet it has been the most neglected, until Dr. Prichard took up the inquiry. Whilst the capaciousness of the skulls of the Negro and European has been measured and compared, but little account has been taken of the workings of the brains which they contained. The colour of the skin, the flatness or projection of the nose, the lankness or crispness of the hair, the straightness or curvature of the limbs, have been scrutinised and contrasted, as if these alone constituted the proper description of Man ; though it is surely in his mental cha racter and its manifestations, that the attri butes of humanity peculiarly consist.