ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
405 
for observation and tlie illumination of the body is not interfered with 
by the instrument. 
Bernard, P. — Note sur un Microscope compose du 18 me siecle. Lille, 1800, 8vo. 
(2) Eye-pieces and Objectives. 
Johnson, C. — The American Objective as compared with the German. 
Maryland Med. Journ ., XXI. (1889) p. 130. 
C3) Illuminating and other Apparatus. 
Bausch and Lomb’s Condenser Mounting with Iris Diaphragm. — 
In addition to the form of this device which we figured in this Journal, 
1890, p. 508, a simpler and less expensive form has been issued by the 
firm, as shown in fig. 48. 
Fig. 48. 
New Lens-holder with Stand.* — M. L. Malassez has constructed a 
new holder for use with his erecting objectives of long focus. Like 
the lens-holders in common use, this serves to support ordinary 
lenses, but will also hold a Microscope-tube provided with the new 
lenses. It consists of a triangular foot of cast iron and lead, very 
heavy, giving great stability with considerable space for manipula- 
tion. It is covered with india-rubber underneath, to avoid vibration 
being communicated to the arm of the lens-holder from the table. On 
this foot is the triangular standard with rack, on which the socket 
carrying the horizontal arm moves. This arm is not fixed to the socket 
itself, but to a ring which rotates on it. The result is that the arm 
can be turned round the standard, without the latter being displaced, 
so that when, during a dissection for example, it is necessary to dis- 
pense for a moment with lens or Microscope, there is no need to move 
the heavy base, but simply to turn the arm aside. Two fixed stops 
limit the extent of the rotation, and another stop provided with a 
spring enables the arm to be replaced in its original position. The 
friction surface of the ring of the socket is a truncated cone with the 
base below, an arrangement which prevents the oscillations which with 
another form of surface would be produced by the wear and tear of the 
pieces. 
The arm of the lens-holder is long, so that, with the arrangement cf 
* Arch, de Med. Expe'r., i. (1889) pp. 455-7 (1 fig.). 
