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SUMMARY OF CURRENT RESEARCHES RELATING TO 



Ultramicroscopy and Dark-ground Illumination.* — The new 

 catalogue of C. Zeiss not only gives a priced list of all the apparatus 

 required for the above research, but also supplies a very full description 

 of the methods of application, with a full bibliography. The subject is 

 arranged into five parts : (1) General ul train icroscopic apparatus ; (2) 

 Ultramicroscopy for cells, fibres ; (3) Ultramicroscopy for colloids ; 

 (4) Siedentopf 's paraboloidal condenser ; (5) Applying a stop to the 

 immersion-condenser. 



Kaiserling's Universal Projection Apparatus.! — This apparatus 

 made by E. Leitz, of Wetzlar, has been already described in this Journal 

 (1907, p. 627) ; but a new catalogue! explains in detail its application 

 to various kinds of projection. 



Fig. 102. 



1. Microscopic Projection. — Before proceeding to direct projections 

 with the Microscope it is necessary to turn aside lens Q of 400 mm. focus 

 (fig. 102), which, together with the reversing mirror G, is hinged upon 

 the upper steel tube E, after which the optical bench, together with its 

 appurtenances, may be brought into the path of the light. The small 

 optical bench B l (fig. 103), has three stands, which may be moved along 

 the larger optical bench by a rack-and-pinion gear; The first stand, 

 reckoned from lens K 3 , is fitted with an iris-diaphragm, the second with 



* Special Catalogue, C. Zeiss, Jena and London, etc. (English version), 1907. 

 The various parts are numbered Mikr. 227-31. 



t Universal Projection Apparatus. E. Leitz, London (Engish version), 1908. 



