Page:Popular Science Monthly Volume 36.djvu/686

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668
THE POPULAR SCIENCE MONTHLY.

of the head and body being a little more than three inches, and that of the tail being about two inches. Its snout, although long, is not quite so narrow and pointed as that of the erd shrew, and its ears are remarkably small. When it swims, it has a curious habit of spreading out its sides, so as to flatten its body as it floats upon the water" (Wood).

Another kind of shrew which frequents the water is the oared shrew, so called from the oar-like shape of the feet and tail. It is the largest of the British shrews, its total length to the tip of the tail being about five inches and a quarter. The fur on its back is sprinkled with white hairs, and that on the flanks and belly is blackish gray, tinged with yellow. On account of the general dark appearance of its fur, it is sometimes called the "black water shrew." The rustic shrew (Corsira rustica) is found in many parts of England, while in Ireland it replaces the erd shrew.

The smallest mammal known to exist is found among the shrews. This is the Etruscan shrew, and it is found in Italy. Its head and body measure only an inch and a half in length, and its tail adds about an inch more.


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A CHEMICAL PROLOGUE.

By C. HANFORD HENDERSON,

PROFESSOR OF PHYSICS AND CHEMISTRY IN THE PHILADELPHIA MANUAL TRAINING SCHOOL.

THE human infant, during the first few weeks of its life, must be regarded simply as a bundle of possibilities. A bright light, a loud noise, an appreciable degree of heat or of cold, produce, it is true, corresponding reactions. The child blinks, or it starts, or it shrinks, and there is manifest to the most careless observer a general sense of uneasiness. But these reactions must be regarded as purely involuntary. One can not discover in any of them the presence of thought. There is no co-ordination of the faculties. The touch includes anything that may come within reach. It does not act in any way in harmony with the eye. Nor does the gaze become fixed upon any object. The eye wanders from one thing to another without really seeing anything. Similarly with the sense of hearing. Sound is a mere vibration, without any meaning whatever. If it be sufficiently loud, it makes the infant start much as a violent explosion would shake a window or rattle a pile of dishes.

But as the weeks roll by, there comes a marked change. When the child reaches the age of three months the presence of will becomes unmistakable. The faculties begin to act in harmony with