20 THE MICROSCOPICAL NEWS. 
from the temperature of the room up to roo degrees. _It consists 
of a mahogany slide 3” + 114” + ¥, with a flat groove 4,” deep 
for the ordinary glass slide to lay in. In the centre is a round hole 
one inch in diameter, which encloses a copper ring, made by bend- 
ing No. 16 wire into a ring slightly less than the hole, and giving it 
one twist leaving the two ends to pass longitudinally through the 
stage when they are twisted together, leaving a single wire at the 
end about one inch longer, with the end curled round. The stage 
is heated by a spirit lamp held to the twisted wire, and when the 
required temperature is reached the lamp is moved back along the 
wire to a point that will just maintain the temperature. The room 
was 62° F.; the slide was heated to 82°, and the temperature kept 
stationary. It was then heated to 100° F., and kept stationary for 
half-an-hour. In this arrangement the heated wire is isolated from 
the stage, and from the glass slide by means of the wood in which ~ 
it is placed. For purposes of crystallisation, the growth of Torulz, 
Bacteria, and kindred subjects, this form of apparatus will be found 
simple, cleanly, and easily worked. 
Mr. Bell next exhibited a form of stage condenser for illumina- 
ting diatomacez ; the principal point is it will suit any microscope 
which is not fitted with substage arrangements. It is simply an 
addition of a shutter to the hemispherical lens: this shutter is 
easily removable, as it is held to the brass seating of the lens by 
friction, it can be fitted to any lens, though for the best effect the 
lens should not be less than ¥% an inch in clear aperture, and 
slightly less than hemispherical, say of a thickness equal to four- 
fifths the radius. The shutter is similar to that used by Messrs. 
Powell and Lealand. For their substage condenser there is a cen- 
tral aperture and two side ones at right angles to each other, which 
can be used at pleasure. This form gives very satisfactory results, 
and Navicula rhomboides has been resolved with ; by Swift, 
equal to what can be done with same frustules and Powell and 
Lealand’s apparatus complete. 
BIRMINGHAM NATURAL HISTORY AND 
MICROSCOPICAL SOCIEG€Y 
T the meeting of this Society on Tuesday, December 4th, at 
the Mason College, the President (Mr. T. R. Waller) in the 
chair, Professor W. Hillhouse, M.A., F.S.L. (Professor of Botany 
and Vegetable Physiology at the college), delivered a lecture on 
some recent discoveries which he has made in the structure of 
