Page:Popular Science Monthly Volume 37.djvu/735

Rh of the cases and a more judicious proportioning of the measure of treatment to that feature. The gravity of the case appears to vary somewhat according to the part of the body that is bitten. The most dangerous bites were in the head, with which the mortality was 2·36 per cent; next were the hands, 0·69 per cent; and last the body and limbs, 0·27 per cent. The inferior gravity of the last class of bites may, perhaps, be attributed to the action of the clothing in wiping the animal's teeth.

The Unexplored Regions of Canada.—It is commonly supposed that all parts of Canada have been explored and are known. Mr. G. M. Dawson thinks that this opinion is not correct, and that the clearness of the maps, on which it is chiefly founded, is due to their makers having assumed for regions of considerable extent what has not been verified. Probably but little of the regions which are really unknown is agriculturally or climatically attractive; but they may contain mineral wealth, and some of them may in time have value for cultivation. In marking out the districts which he regards as unexplored, the author takes no notice of comparatively small tracts of country lying between explored regions, or of any having an area of less than 7,500 square miles; and he also omits the arctic islands lying to the north of the continent. With these limitations he enumerates and defines sixteen distinct regions in the Dominion concerning which definite and satisfactory information is wanting, varying in area from 7,500 square miles to 289,000 square miles. In all, it may be stated that "while the entire area of the Dominion is computed at 3,470,257 square miles, about 954,000 square miles of the continent alone, exclusive of the inhospitable detached arctic portions, is for all practical purposes entirely unknown. In this estimate the area of the unexplored country is reduced to a minimum by the mode of definition employed. Probably we should be much nearer the mark in assuming it as about one million square miles, or between one third and one fourth of the whole. Till this great aggregate of unknown territory shall have been subjected to examination, or at least till it has been broken up and traversed in many directions by exploratory and survey lines, we must all feel that it stands as a reproach to our want of enterprise and of a justifiable curiosity. In order, however, to properly ascertain and make known the natural resources of the great tracts lying beyond the borders of civilization, such explorations and surveys as are undertaken must be of a truly scientific character."

Crystallization seen in the Act.—The process of crystallization as observed under the microscope is described by Dr. H. Hensoldt in a paper on crystallogenesis. The commencement of the operation is always signaled by the sudden appearance, in the previously clear and colorless field, of innumerable dark points, which, in an incredibly short time, augment in volume, till a diameter of perhaps of a millimetre is reached. It is then observed that the particles are spherical in outline, and that their darkness is only an optical illusion, caused by a broad diffraction-ring, for in reality they are quite transparent. They are evenly distributed over the field, and their "growth"—a kind of spontaneous swelling, which can be plainly followed—is uniform and simultaneous. The particles then appear to become suddenly endowed with polarity; they change their positions, roll about like billiard-balls in every direction, yet always in straight lines. For a moment all seems confusion, but behold! some invisible "floor-master" is asserting his authority, and in another instant we have the first manifestation of a symmetry destined to culminate in that perfect crystalline regularity which has excited the wonder of all ages. The globules, originally scattered all over the field, are now arranged in lines or rows, like so many strings of beads. Some of these rows consist of only three or four globules, in others we can count ten, fifteen, twenty, or more; and it would seem as if each spherical body was surrounded by a delicate film or pellicle, which prevents the dissipation of the internal molecular forces. A series of rapid changes is now inaugurated, which can be followed only with the greatest difficulty. The globules in each line, by a sudden and simultaneous movement, unite and form solid rods, and there are grounds for believing that this solidification is due to the