Page:Popular Science Monthly Volume 42.djvu/70

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the earth. Besides saving from waste the products of decay, these roots must add considerable strength to the weakened trunk. This feature is perhaps all the more significant in view of the mulberry's near kinship with the banyan tree, which makes such wonderful mechanical use of aërial roots.

With regard to the way in which such economizing roots originate, and their physiological significance, it seems clear, as Mr. Sudworth has suggested, that the conditions necessary for their production are essentially the same as those favoring root-production in cuttings and layered branches. That is to say, given a vigorous cambium or similar formative tissue, near a more or less injured region, the presence of moisture for a certain period, and a congenial soil, then adventitious roots may be expected to appear. That in all the cases above cited these conditions were most probably present antecedent to the appearance of the roots seems surely to be a fair inference from all we know regarding them.

When, as in Mr. Buckhout's maple, there is opportunity for dust, etc., to accumulate in a small cleft near the callus, before total separation of the limb, the conditions are practically the same as in those not uncommon cases where seeds are found to sprout in the fork of a tree and grow for a number of years.

Now that the attention of observers has been called to this curious power which trees have of making the best of a bad matter, it will doubtless be found that the phenomenon is of more common occurrence than was at first suspected.



MATHEMATICIANS, doctors, and philosophers have lately enjoyed a rare opportunity to study a new calculating prodigy, a young man twenty-four years old, who performs mentally, with surprising rapidity, operations in arithmetic involving a large number of figures. We purpose, pertinently to his case, to consider the psychological aptitudes which serve as the basis of mental calculation. We shall use in our study the report of the committee of the Academy of Sciences which examined M. Inaudi, and the results of our own personal observations of his powers, by which we are convinced that he can bear comparison, for the extraordinary development of his memory, with all other known calculators. Jacques Inaudi was born at Onorato, in Piedmont, on October 13, 1867, of a family in modest circumstances. He passed his earlier years in tending sheep. At the