The following seems to have been written with some foreboding of the more recent anthropology that "minimizes this difference" between European and Negroid, and regards "the mental gap as more apparent than real, and due rather to experience and training than to innate factors."
"The capacity for spiritual achievement is, I believe, as regards both magnitude and variety, always innate, a gift of Nature, and expressed in the magnitude and weight of the brain and the development of the convolutions, either in the whole or in the single parts. In it, aside from morbid alterations, the individual can bring about no change, neither by addition nor by subtraction. But the degree and the kind of the development of this endowment (Ausbildung dieser Anlage) depends on a thousand other conditions, partly quite beyond the insight and will of the individual—partly, however, subject thereto. All that we call education, culture, social position, example, and, on the part of the individual, good-will, industry, zeal, etc., work for the development of the endowment, and the achievement depends thereon. Endowment, as already said, is unalterable; but the degree of the development and achievement may vary a thousandfold" (p. 165).
On p. 169, Bischoff starts the interesting query, whether any enhancement of the endowment (Steigerung der Anlage) in general or in particular directions, through increase of the brain, in general or in particular parts, be actual or possible in the course of time, along the path of culture (auf dem Wege der Zuchtung). Broca thought that he had observed a change in the skull capacity of Parisians, in the lapse of centuries; but his results (thinks Bischoff) are very far from being sure. Thus far there is no proof of any such possibility. But even if this latter were conceded, Bischoff adds, the actuality of such a change would by no means follow. So great is the present endowment that all progress that can thus far be proved, may be explained through the development of this endowment, and such will, doubtless, for a long time yet, be the case as regards both the individual and the generations (p. 170). We may add that Bischoff has no doubt whatever either of the lesser brain-weight or of the lower mental capacity of the African Negro.
When, now, we ask what is the real significance of these weights, we are fortunately able to refer to the tables of Dr. H. Matiegka, given in Part I. of his researches "Ueber das Hirngewicht, die Schädelkapacität und die Kopfform, sowie deren Beziehungen zur psychischen Thätigkeit des Menschen" (Sitzb. d. kön. böhm. Ges. d. Wiss. 1902). He has arranged 235 brain-weights in six groups, according to occupation, proceeding from the lowest labourers at odd jobs, who could not learn a trade or find steady employment, up to men of notable intellectual power. Here is the table, showing the number in each group and the average weight of brain:
| 14 | Day-labourers | 1410.0 | grams |
| 34 | Labourers | 1433.5 | " |
| 14 | Porters, watchmen, etc. | 1435.7 | " |
| 123 | Mechanics, workers at trades, etc. | 1449.6 | " |
| 28 | Business men, teachers, clerks, professional musicians, photographers, etc. | 1468.5 | " |
| 22 | College-bred scholars, physicians, etc. | 1500.0 | " |
| 235 | Average of all | 1451.5 | grams |
| or 51.20 | oz. |
Here we observe that the excess of this average over that of the 141 Blacks is 4.24 ounces. Also we remark that the average of the lowest of Matiegka's groups, the shiftless and incompetent, is nearly 48.61 ounces, which is much above the average (46.96) yielded by Dr. Russell's 141 measurements of pure Blacks. Look at it another way. The defect of the day-labourer's brain, as compared with the scholar's, in Matiegka's groups, is precisely six per cent. Even if the average white brain weighed only fifty ounces, a defect of six per cent. would reduce it only to forty-seven ounces, which is still above the average of the Blacks. This latter, then, falls appreciably below the lowest white standard.
Once more, we now come to see clearly the immense significance of the admittedly "somewhat less developed Negroid brain." The famous lines of Browning seem to have been written especially for this occasion:
Oh, the little more, and how much it is!
And the little less, and what worlds away!
The difference between the averages of the highest and the lowest of the Matiegka groups is only six per cent.; and yet how infinite its moment for humanity and civilization! The difference meanwhile between the general averages of the White and the Black is little if any less than eight per cent. (52-48 = 4, that is, 1-13 or 7.7 per cent.). Who, then, can compute its import for the history of the race?