Isidore Geoffroy quotes, with complacency, the instance of the Corsican and African stag taken from Europe to these two countries scarcely twenty centuries ago, which form at the present day two clearly distinct varieties. From that the author of the _Histoire Naturelle Générale_ argues rapid and sensible modifications, caused by the action of the medium. But, first of all, the evidence of this fact is simply negative; the old authors, who denied the existence of the stag in Corsica and Africa, were perhaps simply ignorant of it. Then, this introduction, if it did take place, was perhaps performed by means of animals which had been kept in domesticity or captivity for many generations, and consequently, were easily able to change their mode of life directly they recovered their liberty, as we have already said. However this may be, it is simply man himself whom it is necessary to examine, without comparing him to any animal, and without misleading ourselves with the connexion of climates, generally compared too hastily, and with regard to mere equality of temperature. It is sufficient to run over, in Humboldt’s _Cosmos_, the lengthy enumeration of circumstances which make up a climate, in order to understand that all the comparisons which our minds may make between any two regions of the world are, at least, rash. The analogy of two climates is rather a sort of experimental notion, which can only be reasonably deduced by the similarity of the biological as well as the meteorological phenomena of every kind in the two regions to be compared. And when climates shall have been able to change a white man into a black (a fact we energetically deny), must we also lay to the charge of meteorological influence the clear moral aptitude and profound differences of the various species of mankind? Shall we admit that a little more cold or heat will alter the intellect? and why not language? But _we_ are not the first to doubt all these marvels. Bacon[220] and Albin[221] fairly doubted the effect of the sun on the colour of the skin. Camper, who admitted that all varieties come from external influences, acknowledged, and with good faith, that the influences which we can appreciate are not sufficient to explain fully either the prominent jaw-bone in the Negro, the cheek-bone in the Kalmuc, or the obliquity of the eyes in the Chinese and the Malay, etc. We can declare the same about all the other peculiarities of the same order,--the flattening of the nose, the crisped state of the hair, the colouring matter which we find even in the arch of the palate in the Negro, etc.