ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



253 



tubes is retained by means of tlie V-shaped carrier, thus giving absolute 

 security of centering. A specimen of such a microscopic arrangement 

 has been in use at the Vienna Pathological Institute since 1893, and 

 has given great satisfaction. The coarse adjustment of the objective is 

 by rack-and-pinion of sufficient path with long focus, and the fine 

 adjustment is by micrometer screw. The object-stage is easily remov- 

 able, and is adjustable in two directions by screws ; the upper plate 

 is rotatory. Abbe's illuminator is centred by two screws. The Micro- 

 scope with water-chamber is fastened by two bolts to the condenser 

 system, and is easily detached. In its place a shorter water-chamber, 

 a bellows, or a frame for diapositives can be inserted. 



Fig. 57. 



■pp— 



Reichert's Medium Projection Apparatus. — This apparatus (fig. 57) 

 consists of an oak case lined witli asbestos, a three-lensed condenser 

 system of 160 mm. aperture with a large easily slided out water- 

 chamber between the two front lenses, and an arc lamp for rather strong 

 currents up to 40 amperes. The carbon adjustments are done by hand 

 by means of the screw S ; the lamp is regulated by movements vertically 

 and horizontally as well as forwards and backwards, so as to be able 



