342 



ACCESSORY APPARATUS 



a plain glass stage, fig. 293, a, a, so fitted as to slide on in the place 

 of the ordinary sliding stage of a Powell and Lealand or Ross stand. 

 It is thus susceptible of the mechanical motions common to those 

 stages. Its foundation, fig. 293, a, a, is plate glass, about the tenth 

 of an inch thick, in order to give it firmness. But this is too thick 

 to work through with a condenser and high powers, and therefore a 



FIG. 293. Dallinger and Drysdale's moist continuous growing stage. 



circular aperture, 6, is cut through it, and a thin piece of good glass, 

 c, d, e,f, is fixed over the under surface of it with Canada balsam ; 

 this may be as thin as the condenser may require. At the end of 

 the arm a, which extends some distance beyond the stage to the 

 right of the reader, but, when the arrangement is set up on the 

 microscope, to the left of the operator, a brass socket with a ring 

 attached is fixed with marine glue. It is marked in the drawing 

 g, g, g. The object of this ring is to hold a glass 

 vessel, fig. 294, about 1 J or 2 inches deep. It 

 simply drops in, and the top, a, being slightly 

 larger than the ring, g, fig. 293, it is prevented 

 from slipping through. 



-Let us suppose the stage 

 to be in its position on the 

 microscope, and the vessel, 

 fig. 294, inserted in this 

 manner into </, fig. 293. A 

 piece of good new linen is 

 now cut to the shape drawn 

 FIG. 294. FIG. 295. in fig. 297, the part a being 



long enough to reach to the 



end of the glass stage, and then at b bent over, leaving the part in 

 the vessel, fig. 294, which is inserted into g, fig. 293. Its position 

 is indicated in fig. 293 by the clotted lines, h, h, h, &c. But before 

 it is laid upon the stage a circular aperture, d, fig. 297, is cut out, 

 which must be much larger in diameter than the covering glass 

 which it is intended to use. We therefore employ small covers. 



