342 



ACCESSOKY APPARATUS 



:i plain -lass 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 



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



circular aperture. f>. is cut through it, and a thin piece of good glass. 

 <. iJ, 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 

 'I ii '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. Tt is marked in the drawing 



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

 vessel, fig. 2D4. about If or 2 inches deep. Tt 

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

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

 from slipping through. 



Let us suppose the stage 

 to be in its position on the 

 microscope, and the vessel. 

 tig. '294. inserted in this 

 manner into <?, fig. 293. A 

 piece of good new linen is 

 now cut to the shape drawn 

 in (io-. 297, the part ^ being 

 long enough to reach to the 



end of the glass stage, and then al f> I>en1 over, leaving the part in 

 the \essel. MM-. 291. which is inserted into </. iig. 293. Its posit ion 

 i- indicated in Iig. 29.'! by 1 he dotted lines. It, It. It. iVc. I5nt before 

 ii is laid upon the stage a circular aperture, d, fig. 297, is cut nut. 

 which must lie much larger in diameter than the covering glass 

 vhich ii is intended to use. \Ve therefore employ small covers. 



294. 



FIG. 295. 



