[1] We must here inform the reader, once for all, that we shall use, until we say anything to the contrary, the word “_race_,” to designate the different natural groups of the human genus (genus Homo). We intend definitely to prove that these groups constitute veritable _species_. M. de Quatrefages has on this matter reproached us with a confusion, which is accounted for partly by the incorrectness of his quotation. He makes us say, “_The plurality of_ original _races_, otherwise _the plurality of the species_, of the genus ‘man’” (_Unité de l’Espèce Humaine_, 1861, p. 309). It stands as follows in our own text: “The original plurality of races, otherwise the plurality of the _species_ composing the genus ‘_man_,’” etc. It is evident that the confusion which is found in these words is entirely voluntary. [2] One day, I was talking with one of the principal officers of Mehemet-Saïd, at Korosko, in Nubia, about the earthquake which was felt in Lower Egypt on the 12th of October, 1856. He asked me the cause of this phenomenon. I attempted an explanation suited to the understanding of a man who was without the slightest knowledge of this part of scientific information. He replied by telling me the history of the cow who throws the earth from one horn to the other, saying, that this was written, and therefore, such a belief ought to suffice him. [With this opinion may be compared the doctrine of the Muyscas or Chibchas of New Granada, who consider that the earth is supported by Chibchacum, their deity, on pillars of _guiacum_-wood, and that earthquakes are produced by his shifting the burden from one shoulder to the other.--EDITOR.] [3] It is only necessary, in order to be sure of this fact, to glance over the _Bulletins de la Société d’Anthropologie_, the creation of which is due above all to the indefatigable zeal of a partisan of the doctrines which we defend--to M. P. Broca. [4] Anthropology is not the only branch in modern science which opens new paths to the human mind: see Michelet, _L’Insecte_, p. 106; see also Bourdet, _Traité d’éducation positive_, 1863. [5] This name has been definitely adopted in France in preference to that of “Unitarians” (_Unitaires_), used by M. de Gobineau.