ZOOLOGY AND HOTANV, MICROSCOPY, ETC. 



619 



are designed on the Continental Model. The stage is square, the upp<'r 

 surface being faced with ebonite. The size is 4 in. by 4 in. It is 

 made specially large for the convenient use of Petri-dislies, or culture 

 plates. A removable mechanical stage can be fitted at will. A special 

 feature of this stage is that an iris-diaphragm is fitted into the stage, 

 flush with the surface, so that if an Al)be condenser is in use the 

 diaphragm can be closed between the top of the condenser and the 

 sUde when the former is in focus. Tlie coarse-adjustment is by a 

 spiral rack-and-pinion and is accurately fitted so that comparatively high 

 poweTS can be focused thereby. The fine-adjustment is by means of a 



Fig. 82. 



lever and a micrometer-screw which gives a very delicate adjustment. 

 The milled heads are at the side of the instrument, and one is provided 

 on each side of the limb so that it can be worked from either side. The 

 body tube of tlie Microscope is 140 mm. long, with a graduated draw- 

 tube, which can be extended to 200 mm. The sub-stage has a swing- 

 out movement and is focused by means of a rack-and-pinion. It will 

 carry either an Abbe or achromatic condenser. A large size double 

 mirror is provided. The whole instrument is finished in stove black 

 enamel which resists the action of acids and spirits. 



Leitz' Microscope for Examination of Brain Sections.* — This 

 stand (fig. 83) has been designed by Messrs. Leitz for objects of 

 unusually large dimensions, and is especially suitable for the examination 



* E. Leitz, Wetzlar : Special Catalogue (1913), Mikroscope, pp. 86, 87. 



