ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 809 



(2j Eye-pieces and Objectives. 



B f K 1! I L L, T. J — A new Objective. 



[Report of examination of a Zeiss 2 mm. apochromatic objective aJid eye-pieces. 

 " Tile ohjective has shown itself to be of very high ;:,'rade among those of moJern 

 production, but judging by results obtained it cannot reveal anything not 

 lierL-tofore seen under similar circumstances with the best work of at least six 

 opticians."] 



The Microscope, VII. (1887) pp. 233-7. 

 ScHi'LL, P. — TJeber das Centrireu optischer Linsen. (On the centering of optical 

 lenses.) 

 [Practical directions.] 



Central-Ztij. f. Opt. u. Mech., VIII. (1887) pp lSl-2, 194-6 (3 figs.). 



(3) Illuminating- and other Apparatus. 



Bausch and Lomb Condenser and Substage.* — This (fig. 219) con- 

 sists of a condenser and substage, the latter baving five stops, diaphragms 

 and blue glass. The lenses of the condenser are of such a size as to utilize 

 almost all the rays of light which may pass through the substage ring, 

 Ju order that objectives having a large aperture may be used, the condenser 



Fig 219. 



has been made witli a numerical aperture of about 1 ■ 42 (another of 1 • 20 

 is also manufactured). Its volume of light is sufficient with the highest 

 amplification, and although it gives an intense light at the focal point it 

 may be distributed over a large space by varying its distance from the 

 object. It will work both dry and immersion. The mounting of this 

 condenser is new and simple, and is so arranged that the instrument can be 

 used where the substage is adjustable or fixed. The diaphragms are 

 separate. 



Reichert's improved Mechanical Stage.f — Prof. E. F. v. Marxow 

 describes an improvement of Eeichert's mechanical stage which allows it 

 to be fitted to any Microscope without requiring any alteration of the 

 stand. In the original form it will be remembered the stage was fitted to 

 the Microscope by passing the bar projecting from the posterior side of the 

 stage through an aperture cut in the pillar of the Microscojje, the bar 

 having rackwork on it by which the stage was moved backwards and for- 

 wards. In the new form the pillar is not required to be pierced, but the 

 stage is clamped to the pillar. 



The posterior part of the stage (fig. 220) consists of two parallel bars 

 d d' on the upper surface of which is rackwork. These bars are joined 

 together by the pieces c c' and gg', the former being hollowed oiit in order 



* The Microscope, vii. (1887) p. 10 (1 fig.). 



+ ZLitbchr. f. Wiss. Mikr., iv. (1887) pp. 2o-o() (1 fig.). 



