Pedagogical Anthropology

by Maria Montessori

This maximum dimension (the biacromial distance) may be regarded as an index of the skeletal development; and Godin takes its proportion to the transverse thoracic diameter (the horizontal distance between the two vertical lines drawn from the arm-pits, in the plane of the mammary papillæ, see Chapter VII, Technique) in order to estimate the proportional relation between the skeleton and the organs of respiration. Since in the course of growth the thorax broadens, that is, the transverse diameter increases more than the antero-posterior, we should expect to find that in the course of evolution, the difference between the transverse development of the skeleton and the lateral development of the thorax steadily diminishes.

It happens, on the contrary, that from the age of ten years onward, during the whole puberal development, the transverse diameter of the thorax steadily becomes less, as compared with the breadth of the shoulders, so much so that if the difference was at first 97 millimetres, it becomes finally 116 millimetres. According to Godin, this indicates that the thorax does not obey the harmonic laws of the development of the skeleton as a whole, but that, owing to causes of adaptation (the school!) it remains definitely inferior to the development which it might have attained, and consequently results in throwing the organism out of its physiological equilibrium. In fact, if we make men raise their arms, especially men of the student class, a certain hollowness, which is æsthetically displeasing, is revealed along the sides of the thorax. This deficiency is corroborated, according to Godin's studies, by his observation of another correspondence in the measurements of the thorax. In addition to the customary measurements, Godin introduced, besides the well-known and classic thoracic perimeter—which is the circumference taken in the horizontal plane passing through the nipples—two other circumferences: one of them higher up, the subaxillary circumference, which includes a large proportion of the pectoral and dorsal muscles; and the other lower down, the submammary circumference, which determines solely the measurement of the thoracic skeleton, since the intercostal muscles are practically the only ones which descend to this level. These two circumferences are to be considered together, according to Godin, as expressing the relation between the organs of respiration and the muscular mass. In complete repose, the subaxillary circumference is much greater than the submammary; but at the moment of maximum inspiration the latter should become equal to the former; hence, the difference between the submammary circumference in repose and during inspiration furnishes an indirect index of the respiratory capacity, and the subaxillary circumference is a test of individual capacity. Godin notes that inspiration almost never succeeds in attaining an equality between the two circumferences.

Shape of the Thorax.—In regard to the shape, which stands in relation to the thoracic index, it is found to vary according to individual types; in fact the index itself, although showing a mean average of 75, oscillates between the extremes of 65 and 85. As a general rule, the brachycephalic races have a deeper thorax, i.e., having a cross-section of more rounded form; the dolichocephalics, on the contrary, have a more flattened thorax in the antero-posterior direction (these races, such as the negroes, are more predisposed to contract pulmonary tuberculosis). Consequently there is a correspondence in type between the head and the thorax. In the measurements taken by me among the women of Latium the results show that the brachycephalics had an average depth of thorax amounting to 188 millimetres and the dolichocephalics only 181 millimetres, while the transverse diameters were very nearly equal: 241 millimetres in the brachycephalics, and 240 millimetres in the dolichocephalics. Hence, the resultant thoracic index of 78 for the brachycephalics and 75 for the dolichocephalics.

Such differences in the index indicate also differences in the formation of the thorax: that it is more or less flattened in the dolichocephalics, and more prominent in the brachycephalics. There is a corresponding diversity of form in the breasts of the women: the dolichocephalic races have more elongated breasts (pear-shaped), the brachycephalics more rounded.

The shape of the thoracic section is at the present time taken into careful consideration, especially in medicine, because it is apt to reveal predispositions to diseases.

It may be obtained by the aid of the cyrtometer (see chapter on Technique). At the present day, however, exceedingly complicated instruments have been constructed, which, by the aid of recording indexes, give a direct representation of the shape of the thoracic perimeter, together with its modifications and respiratory oscillations.

Since these instruments are, for the present, very far removed from widespread practical use, we may adopt as an excellent method for determining the shape and, at the same time, the dimensions of the thorax, that of Maurel, in his research regarding "the square surface of the thoracic section."

Having determined the anthropometric points, Maurel passes strips of metal (stiff enough to retain the shape given them) around the thorax, after the fashion of a tape-measure, first around one half, and then around the other.

Next he places these metal strips (still retaining the shape given them by contact with the thorax), upon a sheet of especially prepared paper, marked in squares, and traces upon it the inner outline of the strips.