ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
673 
MICROSCOPY. 
a. Instruments, Accessories, &c.* 
(1) Stands. 
Horizontal Microscope.^ — Mr. C. R. Barnes describes a horizontal 
Microscope for the measurement of the vertical growth of plants, &c. 
The arrangement is, on the whole, similar to that illustrated in Pfeifer’s 
‘ Physiologie,’ ii. p. 85, fig. 8, which is the form used in the Leipzig 
laboratory. For the present instrument, however, the author claims 
several points of superiority. The base is a large lead-filled brass tripod 
with levelling screws. From this rises a tube 3 cm. in external dia- 
meter, sawed at the top, where it is pinched by a screw collar. A nickel 
draw-tube, 22 cm. long, slides in the outer tube, and can be adjusted in 
height by means of the screw collar. At the upper end of the draw-tube 
is a pinion which engages a rack on a triangular slide. This rack and 
pinion serve to accurately ndjust the Microscope after it has been roughly 
brought to the required height by means of the draw-tube. 
At right angles to the triangular slide is a tube in which the body- 
tube for focusing slides by means of a rack and pinion. Above the 
pinion is a spirit-level accurately parallel to the body-tube, so that the 
latter can be set horizontal by means of the levelling screws. 
The optical parts consist of a 2-in. eye-piece, 1-in. and 3-in. objec- 
tives. A micrometer divided into tenths of a millimetre is fixed in the 
focus of the ocular lens of the eye-piece. 
(2) Eye-pieces and Objectives. 
Demonstration Eye-piece4 — Dr. M. Kuznitzky describes a modified 
form of the eye-piece devised by Prof. Pfitzner, in which the end of a 
pointer can be brought into the centre of the field 
in order, for demonstration purposes, to mark a 
certain spot in the preparation. In Prof. Pfitzner’s 
apparatus the movement of the pointer was effected 
by a lever actuated by a knob on the side of the 
eye-piece. In the modified apparatus, as seen in 
fig. 94, the side knob and lever are replaced by 
a vertical rod, at the lower end of which is the 
pointer projecting horizontally as far as the centre 
of the field of view. The upper end of the rod 
passes through the upper plate of the eye-piece 
and carries a knob, by turning which the pointer 
can be brought at will into the field of view or 
beneath the diaphragm. The knob projects so 
little above the eye-piece as not to interfere with ob- 
servation through the Microscope. Many English 
workers will here recognise an old friend. 
* This subdivision contains (1) Stands ; (2) Eye-pieces and Objectives ; (3) Illu- 
minating and other Apparatus; (4) Photomicrography; (5) Microscopical Optics 
and Manipulation ; (6) Miscellaneous. f Bot. Gaz, xxii. (1896) pp. 55-6. 
X Zeitschr. f. wiss. Mikr., xiii. (1896) pp. 145-6. 
Fig. 94. 
