The anatomy of races has been largely written about, and yet we may even now offer this subject to the serious study of anthropologists; perhaps, also, in carrying their attention farther than the skin, the encephalic mass and the skeleton, which have been nearly the sole objects of study up to the present time, they will find in all systems dissimilarities of the same order, and as clearly defined.[108] These differences and varieties are such that they are obvious, and at once appreciated even by ignorant persons,[109]--they are such that the most eminent monogenists agree in regarding them as everywhere sufficient to make a difference in species, or even in genus itself. They refer to every point of organisation, and we shall see farther on that they are found to be as decided and as palpable both in the mind and in the natural constitution. We do not pretend to speak of all of them in this place, not even to enumerate them; we shall merely quote the principal points, or those which appear to deserve some special remark. The number of those which exist, or which are believed to exist,--for this is a necessary restriction,--is immense; in fact, if we are the first to admit that there is an infinite variety of differences, considerable in themselves, between the various kinds of men, we also wish to avoid falling into the errors which are so often committed, and which happen from the small number of facts which have been observed, the investigators having often given the value of general facts to individual observation. We find more than one example of these hasty opinions in the history of anthropological studies. Towards the end of the last century, when the colour of the Negro had already been for a hundred years the dominant study of the scientific world of Europe,[110] a certain Kluegel affirmed (in the _Encyclopédie de Berlin_, 1782) that the lips of the Ethiopian were of a fine red colour. A great commotion arose; Sömmering himself was roused; he wrote everywhere, sought for information, and demanded fresh intelligence, which, quite naturally, was found to be contrary to the opinion expressed by Kluegel. In fact, we know that in the Negro the colouring matter extends to most of the mucous membranes whose structure resembles that of the skin. The lips are generally black, and we usually find upon the gums, and even upon the palate, a non-continuous coloured membrane, which forms spots of a deep violet colour. Kluegel had concluded too hastily from some particular fact; he had in his mind, very probably, some Negro with lips, gums, and tongue of a fine rose colour, contrasting as much as possible with the black of his skin. We have had occasion ourselves to observe a similar case as regards a native of Soudan, who was also affected with a sort of partial albinoism of the buccal mucous membrane.