51S 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



length for a Bpark-image. The rays of selected wave-length emerg- 

 ing out of the collector then fall on the reflexion prism P, and are 

 thereby conducted to the Microscope condenser. Fig. 112 (one-tenth 

 full size) shows the installation of the entire apparatus ; abed is the 

 Stage-plate for the Microscope and camera, with the slots for the 

 position-screws of the foot-plate and the camera ; it is set up on a table of 

 ordinary height ; eff/h is the stage-plate for the illuminating apparatus, 

 with slots for its screws ; it is set up on a table or cabinet '!'•'> cm. 

 lower than the above mentioned table. A lamp (e.g. an incandescent) 

 is set up at L x or L 2 for examination of the object, with an achromat. 

 If the lamp is placed at L x the rays are reflected at the last face of 

 the prism P 2 laterally in the direction of the axis of the collector K, 

 and reach the condenser of the Microscope after another reflexion 

 at the prism P. If the lamp is placed at L 2 its rays fall direct on the 

 prism P. This light must, of course, be removed when the ultra-violet 

 light is used. A fluorescent screen i serves, on setting up the apparatus, 

 to orientate in the spark-spectrum. Zeiss' catalogue gives full particu- 

 lars of the lenses and all auxiliaries. A. Kohler,* who has both made a 

 long series of investigations and has designed the apparatus, relates the 

 history of his researches. He gives six plates, all of well-known objects, 

 such as Pleurosigma angulatum, to illustrate his results. 



Fig. 113. 



Leitz' "Universal" Microphotographic Apparatus.! — This is 

 described by F. Gr. Kohl, but will now also be found in the latest 



* Zeitschr. wiss. Mikrosk., xxi. (1904) pp. 129-65. 273-304 (6 plates of photo- 

 micrographs). Also as a separate pamphlet, with title Mikrophotographische 

 Untersuchungen mit Ultraviolettem Licht. 



t Zeitschr. wiss. Mikrosk., xxi. (1905) pp. 305-13 (3 figs.). 



