ANIMALCULE CAGE WITH SCKEW. 
65 
87. Compressor. It is often required to tear up delicate 
portions of tissue upon the field of the microscope, or to fioat 
them out, as it were, from the general substance under exam- 
ination, by pressing down the thin glass which covers them ; 
many parts of plants are also better seen when slightly com- 
pressed. 
Fig. 33. 
The compressor, Fig. 33, enables us to apply any amount of 
graduated pressure upon the thin glass which covers the object. 
The lever bears at one end a fiat brass ring, which moves on a 
universal joint, and which can be elevated or depressed by 
turning the screw at the other end of the lever. When the 
screw is loosened the lever can be turned around on the pivot 
which secures it to the plate ; the ring being thus turned away, 
the object on the glass plate, which covers the opening in the 
compressor, can be changed. 
If desired, an ordinary slide can be placed upon the plate of 
the compressor, and the cover pressed down upon the obj ect on 
the slide. Generally a plate of glass is cemented over the 
opening in the compressor, and a circle of thin glass is cemented 
to the movable ring attached to the lever. These glasses can 
be easily removed, if desired, or their places supplied by new 
ones, if they chance to be broken. 
88. Atiimalciile Cage witli Screw. The animalcule cage 
shown at Fig. 31, consists of ^4. 
a brass plate, or slide, carry- 
ing a short cylinder, which 
supports a circular plate of 
glass, over which fits a cap 
bearing a circle of thin glass / a screw collar retains the cap in 
place, and, when screwed down upon it, produces moderate 
CATALOGUE OF ACHROMATIC MICROSCOPES. 
5 
