796 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
mechanism to tlie solid part of the stage has been so reduced in strength 
that with very little use it has become so loose and shaky as to be 
unserviceable. 
In the new stage here shown (fig. 90) it has been the aim of Mr. W. 
H. Bulloch to correct the defects above noted by the application of 
dovetail slides to the forward and backward motions, which also provide 
a firmer support for the lateral motions. 
(4) Photomicrography. 
Photomicrography at Medical Congress of Berlin, 1890.* — In his 
review of the photomicrographic apparatus and photographs exhibited at 
Berlin during the sitting of the International Medical Congress, Dr. R. 
Neuhauss does not seem to have found much that was worth more than a 
general description. The well-known makers Zeiss, Leitz, Klonne and 
Muller, and Hartnack were, of course, in evidence with their well- 
known apparatus. A. Stegemann exhibited a base-board by which the 
camera could be moved from the horizontal to the vertical position ; 
P. Thate, a magnesium flash-light apparatus; and Carl Gunther, a 
cabinet for drying plates, capable of holding 24 plates 13 X 21 cm. in 
size. A strong current of air, kept up by means of a lamp fitted to the 
lid, dries the plates in 3 to 6 hours. Among the photographs may be 
mentioned those of Prof. Loefller, showing the flagella of bacteria ; the 
instantaneous photographs of living infusoria obtained with the flash- 
light of Duncker. The difficulty experienced with the ultra-violet rays 
was avoided by filtering through a Chinin filter. Prof. Babes, of 
Bucharest, is severely handled by the writer, who attributes to the photo- 
graphs almost every possible fault. It would seem, however, that taken 
all round, photomicrography is greatly advancing. 
Marktanner-Turneretscher’s ‘Photomicrography.’! — This recent 
manual on photomicrography is specially addressed to those who are 
desirous of showing the results of their own work by means of photography, 
and of attaining this object with the least expenditure of time and 
trouble. After reviewing and discussing the various apparatus necessary 
for photomicrography the author proceeds to the chief methods and 
explains the dry-plate, the wet-plate and the positive processes, and then 
indicates certain defects which frequently occur, and the means for their 
avoidance. The work ends with describing how to show photographic 
preparations by the aid of the magic lantern. The book is copiously 
illustrated, and contains an excellent list of works of reference. 
Absorption-plates.^ — In order to absorb ultra-violet rays A. Miethe 
employs gelatin plates made as follows : — Gelatin 2 grm., glycerin 2 grm., 
water 25 ccm., aesculin 0 * 059. The gelatin is dissolved in 15 ccm. water, 
then are added the glycerin and the aesculin, dissolved in 10 ccm. water; 
the whole is then filtered through flannel. Glass plates are covered 
with a pretty thick layer of this mixture, which is then allowed to set 
and dry in a dust-free place. In order to completely absorb the ultra- 
* Zeitschr. f. Wiss. Mikr., vii. (1890) pp. 145-50. 
f ‘ Die Mikrophotograpkie,’ Halle, 1890, 344 pp., 195 engravings, and 2 pis. 
X Photogr. Wochenbl., 1890, No. 18. Cf. Zeitschr. f. Wiss. Mikr., vii, (18S0) 
p. 187. 
