668 THE POPULAR SCIENCE MONTHLY. 



of the head and body being a little niore 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 curi- 

 ous 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. 



A CHEMICAL PROLOGUE. 



By C. HANFORD HENDERSON, 



PROFESSOR OF PHTSICS 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, pro- 

 duce, it is true, corresponding reactions. The child blinks, or it 

 starts, or it shrinks, and there is manifest to the most careless ob- 

 server 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. Simi- 

 larly 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 be- 

 comes unmistakable. The faculties begin to act in harmony with 



