ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
519 
which can he adjusted on the optic axial figure by means of the rack and 
pinion of the draw-tube. 
Fig. 55 shows the medium size model which is generally similar to 
the preceding. It differs from it only in being of smaller size, and in 
having no Amici auxiliary objective. Instead it is arranged for the 
“ axial image eye-piece,” and consequently has no draw-tube. 
The small model is of the English tripod form. The polarizer and 
condenser of aperture 1 • 0 are fastened in one socket, and can be rotated 
by an arm. When drawn down in the socket a few millimetres, so 
that the condensing lens comes beneath the stage-plate, they can be 
shifted to one side by a lever. The stage is movable, and is pro- 
vided with a divided circle. The body-tube can only be moved by rack 
and pinion, but the mechanism is sufficiently rigid to allow of the use 
of objectives, up to a focal length of 4 mm. At the upper end of the 
tube is a divided circle for the analyser, and at the lower end are the 
centering arrangement and the slit for the Biot-Klein quartz plate. 
(2) Eye-pieces and Objectives. 
New Objective Changer.* — The firm of Klonne and Muller have 
recently brought out an apparatus which is intended for the rapid and 
easy substitution of objectives. The apparatus is constructed something 
like a pair of pincers, the upper limb of which screws on by means 
of an arrangement like that of the ordinary revolver nose-piece to the 
Microscope-tube. From the under side of this upper limb a conical 
piece, which is encircled by the adapter-ring screwed on to the objective, 
projects downwards. 
The two limbs of the apparatus are kept firmly together by means 
of a spring. In order to insert or change an objective it is merely 
necessary to press the limbs together and then put the objective into the 
half-collar of the lower limb. 
The apparatus can be used in any position of the Microscope, and 
can be fitted with a centering arrangement. 
C3) Illuminating’ and other Apparatus. 
On a new arrangement in Microscopes for the rapid change from 
parallel to convergent light.f — Herr ft. Brunnee, of the firm of Voigt 
Fig. 56. Fig. 57. 
G 
and Hochgesang, in Gottingen, has devised a method for the rapid 
change from parallel to convergent light, which he claims to be superior 
* Central-Ztg. f. Optik u. Mech., xii. (1891) p. 46 (1 fig.), 
t Zeitschr. f. Instrumentenk., xi. (1891) p. 136. 
