25« 



PROJECTION MICROSCOPE 



[CH, IX 



(Zeit. wiss. Mikr., 1893, p. 152, J. R. M. S. , '894, p. 112). It consists 

 of a metal box with glass covers. Through this box is circulated cold 

 water, and the specimen rests directly on the cooler. With this the 

 temperature at the focus of the special condenser (§412) rarely 

 exceeds 27 centigrade. 



Fig. 209. 



Fig 209. Spencer Winkel Mechanical Stage. [Spencer Lens Co. | This stage is 

 convenient for use with the projection microscope as it can be attached to any square 

 stage and has a great range of motion. This large range is especially necessary 

 for series of 'organs or embryos. For the projection microscope it would be better 

 to have both milled heads for moving the stage on the side as in the next. 



§ 414. Stage for Specimens.— This should be large and prefer- 

 ably square or oblong. The central opening should be 50 to 60 mm. in 

 diameter, and have a large iris to lessen this diameter at will. The 

 specimen stage should be on an independent support and adapted for 

 independent motion. This is necessary so that all objects capable of 

 projection may be used on the stage and moved far enough from the 



