It is equally known that Mulattoes and Mulatresses are very prolific in their recrossings with the parent races. The great number of individuals of every shade, designated by the name Quadroon, Quinterons, Tercerons, Griffes, Marabouts, Cabres, etc., and by the collective name of _mixed blood_, proves it. The hybridity of Whites and Negroes is thus, at least, equal to what we described in animals by the name of _paragenesic hybridity_. The question now arises, whether it be eugenesic, that is to say, whether Mulattoes and Mulatresses of the first degree are indefinitely prolific between themselves. It would be imprudent to restrict ourselves to superficial observations, though positive observations are with difficulty collected. Mulattoes of the first degree are not a well defined and circumscribed caste, like the whites and negroes of pure blood. Mulatresses prefer to unite themselves with the white or with mestizoes whiter than themselves. Mulattoes are thus frequently obliged to intermix with either pure negresses, or with mulatresses issued from a recrossing with the Negro race. There are, nevertheless, a goodly number of unions between the mestizos of the first degree; but the individuals issued from these unions have no longer the same chances of intermarrying as those of the first generation. The number of individuals of the first degree must, therefore, rapidly decrease from generation to generation, and the result is, that even if these cross-breeds were indefinitely prolific between themselves, we could only, by way of exception, find mulattoes issued in a direct line to the third or fourth generation, from the direct and exclusive union of mestizoes of the first degree. To give to the question at issue a rigorous solution, it is necessary to study during several generations a population exclusively composed of mulattoes of the _first degree_. This experience can never be obtained. We find, indeed, at Hayti, a population nearly composed of coloured individuals. But these coloured men are mestizos of every shade, and if this hybrid nation were to subsist in perfect prosperity during several generations, the unlimited prolifickness of mestizos of the first degree between themselves would not thereby be demonstrated.