.20 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



The camera-neck is provided with a screw-thread on which, by means of 

 an adapter ring, photographic objectives can be fixed. This arrange- 

 ment also affords facilities for the application of Edinger's apparatus as 

 well as for photographic purposes. For stereoscopic photography the 

 erect stage is provided with a cross-slit so that the preparation can 

 be pushed in two directions. Reflected light can be used with the 

 vertically placed camera, and the foot-plate with the object is then pushed 

 up to the ground-glass disc ready for the stereoscopic arrangement. 



Fig. 115. 



Crosbie, F. — Directions for Photomicrography. Lancet, 1903, p. 233' 



Ives, F. E. — Eine photomikrographische Vorrichtung. 



Zeits. f. Opt. u. Mech., xxiv. (1903) p. 3. 

 „ Stereoscopic Photomicrography with high powers. 



Trans. Amer. Micr. Soc, xxiv. (1902) p. 23. 



Leiss, C— TJber eine neue Camera zur stereoskopischen Abbildung mikroskopischer 

 und makroskopischer Objekte. Zeitschr. f. Instrumentenh., xxiv. (1904) p. 61. 



(5) Microscopical Optics and Manipulation. 



Dark Field Illumination.* — C. Troester describes this method for 

 the observation of living and unstained preparations of bacteria. It 

 consists in showing a light object on a dark ground, and is obtained by 

 shutting out the axial portion of the cone of light that comes from the 

 condenser by means of a centrally placed screen, so that no direct light 

 reaches the ocular. He obtains excellent results by allowing sunlight 

 to pass through a spherical flask filled with water, and placed in the 



* Centralbl. Bakt., 2'* Abt., xiv. (1905) p. 511. 



