In discussing the cranial cavity, our special object is to supply the deficiency of information upon the volume and weight of the brain. Now, from this point of view, we may easily fall into error. The bony cabinet and its contents are developed, to a certain extent at least, independently. This is very clearly demonstrated by a fact which was observed by Gratiolet, and is too frequently forgotten. The subject is an infant in whom the cranium presented the normal conformation. The brain was, nevertheless, almost entirely wanting. In well-formed men the sinuses and coverings of the brain may very easily be more or less developed according to the individual or race, and influence the relative dimensions of the brain.

Moreover, the exact measurement of the capacity of the cranium is attended by difficulties which have not yet been entirely surmounted. In spite of the improvements introduced by M. Broca in his method of measuring with shot, consecutive measurements of the same cranium by the same observer will vary considerably in the result.

Again, there are peculiarities to be taken into consideration, the importance of which has long been neglected. We have known for several years that the stature has an influence upon the weight of the brain. It cannot be without influence upon the cavity by which the latter is enclosed. M. Broca has shown that sex is of itself a cause of variation. In the woman the mean cranial capacity is always less than in the man, and the difference varies between different races.

Nevertheless, in examining a sufficient number of skulls, the causes of error may counterbalance each other, and the means may be accepted as giving results sufficiently near the truth. The results obtained by the same observer are especially favourable for comparison, and from them certain results may be obtained. There is no reason, therefore, why the cranial capacity should not be considered as a character well worthy of study. But its importance must not be exaggerated.

M. Broca arrived at the following result, in considering the distinction of extreme races. The cranial capacity of the Australian being represented by 100, that of the African Negro is 111·60, and that of fair European races 124·8.

I borrow from my eminent colleague the following table, published by M. Topinard in his Anthropologie. This table gives the mean cranial capacity, in cubic centimetres, for a certain number of races in both sexes. I have merely substituted the serial order in the men for the almost geographical division of the author, and calculated the difference between the sexes.

RACES.MEN.WOMEN.DIFFERENCE.
Cavern of Homme-Mort. Neolithic16161507109
Gallo-Bretons15991426173
Auvergnats15981445153
Spanish Basques15741356218
Bas-Bretons15641366198
Contemporary Parisians15581337221
Guanches15571353204
Corsicans15521367185
Esquimaux15391428111
Chinese15181383135
Merovingians15041361143
New Caledonians14601330130
Negroes of West Africa14301281179
Tasmanians14521201251
Australians13471181156
Nubians1329129831

We here observe facts of intercrossing similar to those which I have so often pointed out. The Merovingians, a white race of the first order, are placed between the yellow Chinese and the New Caledonians, Melanesian Negroes.

But the chief value of this table is to show into what serious errors an estimation of the intellectual development of a race from its cranial capacity would lead us. By such an estimation, the troglodytes of the cavern of L’Homme-Mort would be superior to all races enumerated in the table, including contemporary Parisians, and the Chinese would come after the Esquimaux. The French populations occupy, it is true, the upper portion of the table, and the several Negro races are at the bottom. But here, again, when we find the Nubians following closely upon the Australians, we must confess that there can be no real relation between the dimensions of the cranial capacity and social development. We meet, moreover, with similar questions when we turn our attention to the brain.

The following table, which I borrow from Morton, is as instructive as the preceding. It includes a greater number of races. Moreover, the American savant has not only given the means, but also the maxima and minima as established by his researches. His measurements are given in cubic inches. As they are only required for comparison with those of other observers, I have not reduced them to cubic centimetres. I have again confined myself to arranging the means in a descending series, and to calculating the differences between the maxima and minima.