104 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



lenses. The Microscope stand consists of two parts : (1) the object- 

 stage with Abbe's illuminating apparatus and iris diaphragm ; and (2) 

 the tube with the adjustments, rack-and-pinion for the coarse, and 

 micrometer screw for the fine. The object-stage is movable by a simple 

 method. The Microscope parts run on iron tongues and can easily be 

 exchanged for the apparatus for the projection of photographic slides. 

 All other apparatus and objects for projection can be easily applied. 

 The instrument also lends itself to photomicrography if it is connected 

 with a corresponding camera. The apparatus can be used both with 

 apochromatic and the stronger achromatic objectives in conjunction with 

 projection oculars ; it can also be used with the weaker achromatic and 

 photomicrographic objectives without oculars. 



New Microscope Lamp.* — Prof. A. Meyer, in carrying out his re- 

 searches on the structure of the bacterial cell, experienced the need of 

 a suitable substitute for strong sunlight, and devised the following 



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i t? 



^\ 



jL 



rfe^r 



2l 



Fig. 25. 



apparatus, which gave excellent results: — The source of light is an 

 incandescent gas-lamp mounted on a tripod. The light is placed in 

 the focus of a parabolic mirror P, which can be raised or lowered on the 

 pillar of the tripod-stand, fig. 25. The rays pass through a ground-glass 

 plate M to the mirror of the Microscope S. The grain of the gruund- 

 glass plate is very fine. B is a screen to intercept the light coming to the 

 eyes of the worker. The Microscope is placed from 25 to 35 cm.,, 

 according to the power of the objective in use, from the tripod-stand. 



Seibert's Large Polarising Apparatus. — The polariser, with con- 

 denser combined, is shown in fig. 26, and the analyser in fig. 27. The 

 polariser is pushed into the collar of the diaphragm-holder. The rota- 

 tion direction of the nicol is fixed by the clamping of a screw-head in 

 a groove. The analyser is combined with an ocular fitted with cross- 



• Zcitechr. f. m:es. Mikr.. xviii. (1001) pp. H4-G (1 fig.). 



