ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
365 
By the movement about the pin Z up to a stop, the frame B, with 
the condenser C, can be rotated from the position shown in the figure, 
until the latter is beneath the socket S, when a further pressure on the 
lever H serves to press the condenser up into the socket. The position 
of the condenser in which its axis coincides with that of the body-tube 
is fixed by a pin in the socket fitting into a small groove on the condenser. 
The diaphragm apparatus D is then brought beneath the condenser 
system in the usual way. 
The removal of the condenser is effected by the same manipulations 
in the reverse order. The diaphragm apparatus D is swung to one side, 
the condenser C released from the socket by the lever H, and then 
turned aside out of the optic axis by rotation about the pin Z. 
Fig. 60. 
The apparatus can be provided with a cylinder diaphragm, whose use 
without the condenser is often desired although it may not be considered 
as necessary. This diaphragm, as seen in fig. 60, is an iris-cylinder 
diaphragm with curved lamellae, so that it may be brought close to the 
preparation. When open it allows room for the condenser system, and 
even when the condenser is in position it can be closed slightly before 
touching it. When the condenser is removed, the diaphragm can be 
closed to a diameter of 0*5 mm. The movement of the diaphragm 
is effected by the knob K projecting from the lower flange of the 
socket S. 
New Compressorium.* — Prof. Fr. Sav. Monticelli describes a new 
and simple compressorium. It consists of two parts, a base plate and 
a ring, provided with a screw for applying the pressure. 
The base plate is a rectangular brass plate with rounded angles 
(fig. 61) of dimensions 80 x 57 X 1 mm. In the middle of the plate 
rises a brass ring to a height of 9 mm. (fig. 63, E F), in thickness a 
little over 1/2 mm. and 47 mm. in diameter. On the inside this ring 
carries a screw-thread which does not occupy more than 5 mm. of the 
total height commencing from the upper margin. Within the ring the 
base-plate has a circular aperture 30 mm. in diameter. Bound this 
aperture up to a diameter of 38 mm. the base-plate is cut through half 
* Zeitschr. f. wiss. Mikr., xi. (1895) pp. 454-7. 
