Pedagogical Anthropology

by Maria Montessori

The above mentioned alternation in the growth of the bones must therefore be attributed to an alternation in the action of these various formative elements of the bones.

In the case of two successive long bones (for example, the humerus and radius, the femur and tibia, the metacarpus and phalanges, etc.), they alternate in their growth; while one of them is lengthening, the other is thickening; consequently the growth of a limb in length is not simultaneous in all the bones, but takes place alternately in the successive bones. During the time when the growth devolves upon the longest bone, the limbs show the greatest rate of increase in length, and when, on the contrary, it devolves upon the shortest bone, the growth is less; but in either case it continues to grow.

The growth of the long bones of the limbs proceeds by alternate periods of activity and repose, which succeed each other regularly.

These periods of activity and repose occur inversely in each two successive bones.

The periods of repose from growth in length are utilised for gain in thickness, and reciprocally. The long bones lengthen and thicken alternately, and not simultaneously.

It is only at the age of puberty (fifteenth year) that a complete simultaneity of growth takes place, after which epoch the growth in stature and length of limb diminishes, yielding precedence to that of the vertebral column.

When the complete development of the bodily proportions is attained (eighteenth year), the length of the lower limbs is equal to one-half the stature.

When the upper limbs are extended vertically along the sides of the body, the tip of the middle finger reaches the middle point of the thigh, while the wrist coincides with the ischium (hip-bone). The total spread of the arms is, on an average, equal in length to the stature.

The proportions between the lower limbs and the bust, resulting from the attainment of complete individual development, determine the types of stature: macroscelia and brachyscelia. Since the order of growth as between the two essential portions of stature is now determined, we are able to interpret macroscelia as a phenomenon of infantilism (arrested development of the bust).