3 o THE POPULAR SCIENCE MONTHLY. 



troughs of water so arranged as to imitate as closely as possible the 

 natural conditions necessary for the development and growth of the 

 fish. Properly managed, ninety per cent, of the eggs will hatch out : 

 the young fish are turned into the river when they are about a year 

 old ; if they can be kept two years in tanks large enough, with plenty 

 of running water, so much the better for the prospect of their reach- 

 ing the sea in safety. 



Fig. 5. 



Head of a Kelt. 



When we can make up our minds to keep all our pollutions out of 

 our rivers, and build " salmon-ladders " over all the wears, so as to 

 give the fish a fair field, and enable them to run up-stream unimpeded, 

 then, and then only, shall we see salmon as plentiful throughout the 

 country as it is said to have been in the North a century ago, when 

 apprentices are reputed to have stipulated in their indentures that 

 they should be fed on salmon not more than three days a week. 

 Without this, all our efforts to stock our barren rivers with artificially- 

 bred fry will prove comparatively unavailing. — Nature. 



-+*o~- 



O 



PSYCHOLOGY OF THE SEXES. 1 



By HERBERT SPENCER. 



,NE further instance of the need for psychological inquiries as 

 Vy guides to sociological conclusions may be named — an instance of 

 quite a different kind, but one no less relevant to questions of the time. 

 I refer to the comparative psychology of the sexes. Women, as well as 

 men, are units in a society, and tend by their natures to give that so- 

 ciety certain traits of structure and action. Hence the question, Are 

 the mental natures of men and women the same ? is an important one 

 to the sociologist. If they are, an increase of feminine influence is 

 not likely to affect the social type in a marked manner. If they are 



1 Conclusion of chapter on Mental Science and Sociology. 



