1058 



SUMMARY OF CUERENT RESEARCHES RELATING TO 



Inostranzeff's Double Microscope.* — M. Inostranzeflf " proposes 

 to use the tint and lustre of non-transparent minerals as a means of 

 comparison, by adapting a double Microscope, so that the objectives 

 receive separately the rays proceeding from the minerals studied. 

 The rays are inflected by prisms, so that they reach a single eye- 

 piece, and form two halves of the field of view divided by a fine line. 

 With identical minerals a uniform image is obtained, but the slightest 

 change of shade in any one object causes the line of division and two 

 distinct parts to appear." 



Microscopes with Accessory Stages, — The cutting of series of 

 sections now so much in use necessitates, as mentioned ante p. 153, a 

 considerable increase in the size of the slides on which they are to be 

 mounted, some of those in use at Cambridge being 6 in. x 2 in. with 

 cover-glasses 5 in. X IJ in., and containing it may be 500 sections. 



This of course renders it desirable that the stage of the Microscope 

 should be much wider than ordinarily made, so as to support the slides 

 when the sections at either end are examined. For broad as well as 

 long sections such as brain, the arrangements devised by Schieck and 

 Giacomini and shown ante, p. 515, are very suitable. The extensible 



Fig. 233. 



arms of Schieck's form will not however accommodate the narrow 

 slides used for series of sections, and the supports of Giacomini's are 

 more especially intended for broad and not for long and narrow slides. 

 The increase in the size of the fixed stage is moreover undesirable, what 

 is wanted being some simple and readily adapted addition to a stage 

 which will allow it to be again restored to its normal size when required. 

 This want may be supplied by an adaptation of the device used 

 many years since by Andrew Pritchard and Powell, and applied in 

 more modern times for the attachment of the hand-rests used with 

 German dissecting Microscopes. 



* Illus. Sci. Monthly, iv. (18S5) p. 27. 



