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316 should take into consideration. There are many others to which I can not now refer, but which will naturally occur to the thoughtful anatomist.

In this rapid review of the physical side of our subject the study of these race-characters naturally suggests the vexed question as to the hereditary transmission of acquired peculiarities. This is too large a controversy for us now to engage in, but in the special instances before us there are grounds for the presumption that these characters of microdontism and megacephaly have been acquired at some stage in the ancestral history of humanity, and that they are respectively correlated with diminution of use in the one case and increase of activity in the other. It is a matter of observation that these qualities have become hereditary, and the point at issue is not the fact, but the mechanism of the transmission. We know that use or disuse affects the development of structure in the individual, and it is hard to believe that the persistent disuse of a part through successive generations does not exercise a cumulative influence on its ultimate condition.

There is a statement in reference to one of these characters which has gained an entrance into the text-books, to the effect that the human alveolar arch is shortening, and that the last molar tooth is being crowded out of existence. I have examined 400 crania of men of the long- and round-barrow races, Romano-British and early Saxon, and have not found among all these a single instance of absence of the third molar or of overcrowded teeth. On the other hand, out of 200 ancient Egyptian skulls, nine per cent showed displacement or disease, and 1$1/2$ per cent show the want of one molar tooth. Out of 200 modern English skulls there was no third molar tooth in one per cent. So far this seems to confirm the current opinion.

Yet the whole history of the organism bears testimony to the marvelous persistence of parts in spite of contumely and disuse. Take, for example, the present position of the little toe in man. We know not the condition of this digit in prehistoric man, and have but little information as to its state among savage tribes at the present day, but we do know that in civilized peoples, whose feet are from infancy subjected to conditions of restraint, it is an imperfect organ—

In one per cent of adults the second and third joints have anchylosed, in three per cent the joint between them is rudimentary, with scarcely a trace of a cavity, in twenty per cent of feet the organ has lost one or more of its normal complement of muscles. But though shorn of some of its elements, and with others as mere