122 



THE MICROSCOPE AND ITS REVELATIONS. 



viewed at any desired angle or inclination, when it has been brought into 

 the most suitable azimuth by the rotating of the stage round its vertical 

 axis. 



120. Glass Stage- plate. Every microscope should be furnished with a 

 piece of Plate-glass, about 4 in. by 1-^- in., to one margin of which a nar- 

 row strip of glass is cemented, so as to form a ledge. This is extremely 

 useful, both for laying objects upon (the ledge preventing them to- 

 gether with their covers, if used from sliding down when the Miscro- 

 scope is inclined), and for preserving the stage from injury by the spill- 



FIG: 95. 



Morris's Object-holder. 



ing of sea-water or otner saline or corrosive liquids, when such are in 

 use. Such a plate not only serves for the examination of transparent, 

 but also of opaque objects; for if the Condensing-lens be so adjusted as 

 to throw a side-light upon an object laid upon it, either the Diaphragm- 

 plate or a slip of black-paper will afford a dark back-ground; whilst ob- 

 jects mounted on the small black disks suitable to the Lieberkiihn may 

 conveniently rest on it, instead of being held in the Stage-forceps. 



121. Growing Slide. A number of contrivances have been devised of 

 late years, for the purpose of watching the life-histories of minute aquatic 

 organisms, and of i cultivating ' such as develop and multiply themselves 

 in particular fluids. One of the simplest and most effective, that of Mr. 

 Botterill, represented in Fig. 96, consists of a slip of ebonite, three 

 inches by one, with a central a,perture of 3-4ths of an inch at its under 

 side; this aperture is reduced by a projecting shoulder, whereon is ce- 



BotteriU's Growing-Slide. 



mented a disk of thin glass, which thus forms the bottom of a cell hol- 

 lowed in the thickness of the ebonite slide. On each side of this central 

 cell, a small lateral .cell communicating with it and about l-4th inch in 

 diameter, is drilled-out to the same depth; this serves for the reception 

 of a supply of water or other fluid, which is imparted, as required, to the 



