66 
-ACCESSOEY APPAEATUS. 
pressure sufficient to retain any animalcules in place while they 
are examined. 
This instrument may also be used in some cases instead of 
the “ compressor. 
89: Tlie Simple Animalcule Cage differs from the prece- 
ding only in having the cap retained in place by a cylindrical 
ring, so cut as to act as a spring. The use of this instrument is 
the same as the preceding, though the amount of pressure 
obtained by it is somewhat less. 
90. Stage Forceps. The very convenient instrument shown 
in Fig. 35, can be attached to the stage and made fast by turn- 
ing the screw with a milled head. 
These forceps slide like a pencil in a cylindrical support, 
while the jointed arm and pivot allow of motion in any 
Fig. 35. 
direction. Minute insects or other objects can be held by this 
instrument in any position required. One end of the instru- 
ment carries a needle which can be used for the same i^urpose. 
Hand Forceps, both of brass and of steel, to be used with 
the microscope, are furnished to order. 
91. Frog Plate. For viewing the circulation of the blood, 
the most convenient subject is the common frog. The capillary 
circulation in the thin transparent web of the foot, or in the 
tongue, affords the most interesting exhibition the microscopist 
can enjoy. Some care is required in so arranging the little an- 
imal as to avoid giving him pain, or even stopping the circula- 
tion., by undue pressure on some part of the circulatory system. 
The Feog Plate is an instrument devised to secure these ob- 
jects. An extra stage or brass plate, about two and a half by 
three inches, having a central opening, is attached to the ordi- 
nary stage of the microscope by a short piece of tube attached 
J. & W. GRUNOW k GO’S ILLUSTRATED 
