ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
277 
is its price, whiqh is only 65 francs. One of the specialities of this firm 
are the semi-apochromatic objectives.* 
The firm of Reichert also exhibited two forms of microtome. In one 
of these the object is moved in a vertical direction by a- micrometer- 
screw, up to a limit which can be regulated at will. In the other form, 
the object is moved by micrometer-screw in an inclined plane. 
(3) Instruments and Apparatus of Bacteriology. — The Municipal 
Observatory of Paris exhibited a great variety of apparatus for the 
analysis of air and waters. The so-called aeroscopic methods of Pouchet, 
Pasteur, and others occupied a large place in this exhibition. In the 
most recent registering aeroscope, the plate covered with lichen jelly on 
which the atmospheric dust is deposited, is provided with a clockwork 
arrangement which gives a circular movement to a glass disc on which 
24 divisions, corresponding to the 24 hours of the day, are engraved. 
The firm of Adnet exhibited various sterilizers and stoves of Sorel, 
Schribaux, Miquel, and others. Other exhibitors in this section were 
Wiesnegg, Seibert, and Trouve. 
(4) Micrographic preparations, Photomicrograms, Works of Micro- 
scopy.— In this section an interesting exhibit consisted of 550 prepara- 
tions used by Dr. Van Heurck in the publication of his important work 
on the diatoms of Belgium. 
Prof. Bolsius exhibited his new stage which allows of a lateral 
movement of 72 mm., and 10,000 sections which served in his researches 
on the segmental organs of the Hirudinea. 
The exhibit of Mr. J. Deby included a large International Micro- 
scope of Messrs. Beck, with various accessories, a mineralogical Micro- 
scope of Seibert and Kraft, 50 slides representing the complete anatomy, 
by longitudinal and transversal sections, of Brugmansia Lowoi, 30 sections 
of Hydnojohy ton formicarium and Myrmecodia tuberosa from Japan, &c. 
Other exhibitors in this section were Tempere, Keller, Thum, and 
Moller. 
Photo micrograms were exhibited by Dr. Van Heurck, Jules Van den 
Berghe, Otto Muller, M. Gife, Andrew Pringle, and others. 
Simple Method of Drawing Microscopical Preparations. f — Mr. A. 
Hopewell Smith writes : — “ There has always been a certain amount of 
difficulty attending the use of the camera lucida or Beale’s neutral tint 
reflector for the above purpose. The twisting of the head into an 
uncomfortable position, the great fatigue to the eyes, and the by no 
means easy task of viewing both image and pencil at the same time, add 
to the troubles of making a faithful likeness of the object on paper. 
To those especially who do not possess a camera lucida, or Beale’s 
instrument, and to microscopists generally, I recommend the following 
arrangement of ordinary apparatus : — The Microscope body is placed in 
a horizontal position, and the mirror removed from its substage attach- 
ment. The Microscope slide having been placed on the stage, the 
illuminant (lamplight for choice), is condensed on the slide by 
means of a bull’s-eye in the same way as for photomicrography. 
Care must be taken to centre the light. The concave mirror is then 
* See this Journal, 1890, p. 93. 
t Jouru. Brit. Dental Assoc., xiii. (1892) pp. 78-9. 
