The epidemic of 1853, at New Orleans, allowed Barton to make a scale of mortality on the same principle, and absolutely comparable, and which would take away all doubt in this respect, if any existed.[245] CHAPTER VII. THE INFLUENCE OF HYBRIDITY. We must regard hybridity in a double point of view, as being able or unable to give an indication of the real value of different human races, as compared with the acknowledged natural groups in the greater number of zoological classifications; and on the other hand, we must study hybridity, belonging, as has been asserted, to the creation of new races. It has been said, we repeat, that all men being able to reproduce one with another, the genus _homo_ only constitutes one single family. That this argument should hold good, it was necessary to be proved that among animals (for thence it was that it was borrowed) two well acknowledged species, more different even than two human races, should never be prolific one with the other. Now, this is far from being the case. Isidore Geoffroy Saint-Hilaire, who has treated this subject in a masterly manner in his _Histoire Naturelle Générale_, acknowledges that animals belonging to two different genera can, by a union, produce a mixed breed, which, consequently he calls _bigenerate hybrids_. So we will not give ourselves the trouble of contesting, as some polygenists have done, the universality of reproduction between all races of mankind; we will not ask if every degree of combination has been observed,--the union, for instance, of an Esquimaux with a Negro, an American with an Australian, a Tartar with a Bosjesman. Let us admit, what is, perhaps, hardly the truth, that all races produce one with another,--we will admit all this; and yet it will prove nothing in favour of the monogenists who have brought forward this fact, since we henceforth know that there is no basis in this universality of reproduction for a serious argument,--since we know that two distinct species, two genera, in fact, can produce cross-breeds. This faculty of reproduction has had too much importance given to it,--it is only a function, that is to say, a physiological character quite improper for classification; the existence of _bigenerate hybrids_ shows this sufficiently. It is a bad characteristic, because it is not a constant one; because either the man or the animal does not bear it in him, and that a given uniformity of circumstances is necessary in order to reveal this characteristic to an observer. It is the same with animal forms, which do not countenance in any manner such an observation; it is sufficient to recall the alternating generations of the invertebrata. Where shall we place all these agamous animals? how shall we class these _proscolex_ and _scolex_, which have no sex, and which will never have one? Instead of the idea of fecundity, which is insufficient to characterise a species, we must substitute another, that of the development of the produce.