154 MOSSES AND LIVERWORTS 



scope is a practical necessity. For many years 

 I used a very unpretentious instrument, which 

 even now is not unfrequently brought into requisi- 

 tion. This consists of a magnifying-glass in a 

 light metal frame, at one end of which is a narrow 

 collar, which slips over a screw some two inches 

 long, which is capable of being fixed in an upright 

 position in a small metal stand, and is provided 

 with a nut, so that the lens can be set, in a 

 horizontal position, at any required height. Some 

 such glass and stand can be purchased for a small 

 sum from any microscopical-instrument maker, 

 and not unfrequently the ordinary triple lens, in 

 a horn or tortoise-shell case, forms the magnify- 

 ing-glass a convenient arrangement, as it gives 

 varying powers for different kinds of work. Where 

 very small objects have to be dissected it is useful 

 to have a metal carrier, one end of which slips 

 over the upright screw, as above described, and 

 the other is provided with a round aperture suffi- 

 ciently large to receive one of the high-power 

 lenses, in metal fittings, to be obtained from any 

 of the best makers. Of late I have adopted the 

 more modern binocular dissecting-microscope, 

 which is not only most serviceable in preparing 

 objects for examination, but will also be found 

 invaluable in subsequent mounting operations. 

 Though it is of course much more expensive than 

 the simple apparatus just described, the extra 

 outlay involved is well repaid by the much greater 



