640 THE POPULAR SCIENCE MONTHLY. 



reticence on the part of both those who should receive and those 

 who should impart this instruction. The study of the sexual pro- 

 cesses in the lower plants furnishes an excellent opportunity to 

 get correct ideas concerning sex. The sum total of the informa- 

 tion gained can be greatly increased by the reading that pupils 

 should do after making a thorough study of the object. They 

 can appreciate and remember the illustrations and opinions of 

 others after they have made drawings, written descriptions, and 

 expressed opinions of their own. This is a part of the work that 

 is too frequently omitted. Biological work is often merely a study 

 of types, without sufficient reading to get the connecting facts. 



What this work ought to do for its students, then, is to train 

 their powers of observation ; to teach them how to discover truth 

 for themselves ; to train them in expressing discovered truths in 

 the form of drawings and in written and oral language ; to train 

 them in the power of getting thoughts from the writings of other 

 investigators ; to lead them to see the beauties and harmonies in 

 Nature, and incidentally to give them information concerning 

 life and life problems that will be ever useful to them in any 

 occupation they may choose. 







THE "MUTUAL AID SOCIETY^' OF THE SENSES. 



By Dr. S. MILLINGTON MILLEE. 



"^VrUMEROUS images have been felicitously employed to illus- 

 -L^ trate the significance of the human brain. Drummond, in 

 his book on The Ascent of Man, likens it to a great table-land, 

 traversed by many broad highways, studded with mighty cities, 

 broken up into an endless maze of cross-roads and paths, with 

 some mere faint trails. The cities are the originating centers of 

 gray matter; the highways the constantly traversed paths of 

 ordinary thought ; the cross-roads and bypaths its correlations ; 

 and the trails, the solitary, unfrequented channels of new and 

 original ideas. 



A better simile, perhaps, would be to typify the human brain 

 by some rich mine, with numberless operating centers, connected 

 by subterranean, well-worn passages and alleyways. The number 

 and complexity of these is constantly increasing, as new lodes of 

 ore are opened up, and still newer short cuts are daily blasted out 

 for the economical conveniences of transportation and discovery. 



" Suppose I want to buy a dynamo, as power for an electric 

 light, or for the movement of machinery," said Dr. Walter E. 

 Fernald (I am clothing his idea with my words), the Superintend- 

 ent of the Massachusetts State Asylum for Feeble-minded Chil- 



