On the other hand, every species comprises, independently of the individuals which have preserved their primitive characters, all those which compose the primary, secondary and tertiary, etc., races, derived from the fundamental type.
In other words the species is the unit and the races are the fractions of this unit. Or again, the species is the trunk of the tree, of which the several series of races represent the principal and lesser branches and the twigs. The general unity and relative independence of the trunk and the branches of the tree represent in an obvious manner the connections existing between the species and its races.
CHAPTER IV.
NATURE OF VARIATIONS IN ANIMAL AND VEGETABLE RACES; APPLICATION TO MAN.
I. The meaning of the question stated above is now intelligible. We have to discover whether the human groups, which we know to be distinguished by characters which are often very marked, are fractions of a single unit, branches of the same tree, or so many units of different value, so many trees of various nature.
Historical documents are absolutely incapable of solving this problem. On the other hand, man being the subject of the problem, it is evident that the solution must be sought elsewhere.
Where then must we turn in order to obtain a definite answer to this question which concerns us so closely? Clearly to naturalists and to naturalists alone. The Species and the Race have, for more than two centuries, been the subject of their studies; they have amassed observations, multiplied experiments. They have, in their studies, been guided by a scientific spirit alone, and from being placed beyond the reach of controversy, have preserved all their freedom of judgment. The results thus acquired, deserve the greatest confidence, and supply reliable data for the application of our anthropological method.
Anyone really desirous of forming an opinion upon the unity or multiplicity of the human species, should therefore discover what are the facts and phenomena which characterise race and species in plants and animals; then turn to man and compare the facts and phenomena there presented with those which botanists and zoologists have observed in the other kingdoms. If the facts and phenomena which distinguish the human groups are those which, in other organised and living beings differentiate species, he will then legitimately infer the multiplicity of human species; if, however, these phenomena and facts are characteristic of race in the two inferior kingdoms, he must conclude in favour of specific unity.
It is the pursuance of this course which has convinced me of monogenism, and I am certain the result will be the same with anyone who will follow it.
II. The idea of species rests, as we have seen, upon the two distinct ideas of resemblance and filiation. Let us first turn our attention to the former as being the greater stumbling-block of the two. No one would hesitate to consider two individuals resembling each other very closely as belonging to the same species; if, however, they present somewhat marked differences, and the necessary information is wanting, we hesitate to give our decision in the negative. The mind readily accepts the latter conclusion when man is the object of discussion. A continual, though unconscious study, has endowed us with a perception which appreciates, in those around us, the most delicate gradations in features, the colour of the skin, and in the appearance of the hair. Now this delicacy of appreciation has, in the present instance, a serious inconvenience. It inevitably conduces to the exaggeration of differences existing between different groups, and by this very means leads us to regard them as so many species.