Page:Popular Science Monthly Volume 45.djvu/153

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usually only a few degrees, it is sometimes as much as ten degrees; when the temperature of the air falls below the freezing point and continues to fall, the internal temperature of a tree descends to a point near that where water of vegetation freezes and continues there stationary. Water of vegetation freezes a few tenths of a degree below the freezing point of water. The absolute maximum in the interior temperature of a tree trunk may be produced a considerable time before the maximum of the surrounding air, in consequence of the direct action of the spring sun and air on the leafless trees. During the high summer heats the internal temperature of trees is nearly steady at about 15º C, with a variation of two degrees or more, even under exceptional conditions of variation in the temperature of the air. A large tree is usually a little warmer than the air in the cold months, and a little cooler than the air in the warm months.

Anatomy and Physiology for Young Men.—Writing to the projectors of the Quarter-Century testimonial book to Prof. Burt G. Wilder, Dr. Andrew D. White refers to one point on which Prof. Wilder in the early days was able to render a special service outside of his chosen field. "While the university was in its earliest beginnings, a sort of nebulous state, I was impressed by a remark by Herbert Spencer, in his book on Evolution, as regards the relative values of different kinds of knowledge. He named, among the things to be taught to young men, human anatomy and physiology; and his arguments seem to me now to be absolutely conclusive. For apart from the practical part of these studies, they seem to form a most stimulating beginning to study in natural history generally, not perhaps the logical beginning but the best practical beginning, as is shown by the fact that in all ages the great majority of students of note in natural science have been physicians. Under the influence of this impression I asked Prof. Wilder to give a course of lectures every year to the freshman class on anatomy and physiology. Various arguments might have been used against this; it would have been said that, later in their course, students would have been better prepared to appreciate the fine points of such lectures, and the example of all the older institutions might have been pointed to in which such lectures, when given at all, were generally given as a hurried course in the senior year. But the idea of making an impression in favor of studies in natural science, and especially in human anatomy and physiology, just when young men were most awake to receive them, carried the day with me, and hence my request to Dr. Wilder. He acceded to it at once, and for several years, in fact, until the pressure of other duties drew him from this, he continued these lectures, and it turned out that I had builded better than I knew; not only did the lectures produce admirable practical results, not only did they stimulate in many young men and women a love for natural science and give them an idea of the best methods in its pursuit, but they made a most happy literary impression upon the students generally; the professor's wonderful powers of clear presentation in extemporaneous lectures proved to be a wonderful factor in literary as well as scientific culture. There was another theory of mine proved to be true by the professor; for I had often felt that mere talks about literature, mere writing of essays, the mere study of books of rhetoric, were as nothing in their influence on the plastic minds of students compared with lectures thoroughly good in matter and manner given in their hearing day after day. Naturally I have always felt exceedingly grateful to Prof. Wilder for proving that theory true and at the same time rendering a great service to his students and to the university."

Preparation of Collections.—In his report of the Department of Botany and Forestry in the State Agricultural College of Michigan, Prof. W. J. Beale gives a list of the more common mistakes which young collectors are apt to make in preparing their collections, the perusal of which may give hints of the manner in which the work should be done. They are: The specimen is a mere "snip" of a thing, one little top, destitute of lower leaves, of roots, and root stalks, instead of enough to fill completely a whole sheet. In many instances the plant is pulled into small pieces, and runners, sterile shoots, old leaves, etc., are thrown away; specimens lack fruit, which is often of more importance