522 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



the edge of a table. The camera slides on the rod and can be clamped 

 in any position required. A few inches below the camera, and at a suit- 

 able distance for focusing, slides a stage intended to receive a clear 

 glass plate, a milk-glass plate, a sheet of cardboard, or a metal plate. A 

 hinged arm carries an incandescent lamp for illuminating the upper sur- 

 face. By means of a mirror on a lower stage the lamp-light can be 



directed upwards on to the lower side of 

 a transparent object. Both stages can 

 be clamped at any desired height, they 

 can also be easily swung out' of action, 

 and this is done for photomicrography, 

 the Microscope being then placed on 

 the stool, or floor, vertically under the 

 camera. 



Economical Monochromatic Filters.* 

 J. Jullien gives the following directions 

 for obtaining filters. Take an unexposed 

 sensitive plate, fix it by hyposulphite, 

 and wash it as a negative. Afterwards 

 immerse it for some minutes in a solu- 

 tion of 70 p.c. alcohol, 200 cm. Mars 

 yellow (aniline) 1 gr. Dry it out of 

 reach of dust. This gives filters very 

 nearly approaching the ideal yellow. 

 Other aniline colours, after comparative 

 trials with the spectroscope, will give by 

 this process excellent screens of other 

 tints ; the green is, after the yellow, most 

 frequently employed. 



Kinematography of Fertilisation 

 and Cell-division.! — J. Ries describes 

 how he applied a kinemato-photomi- 

 Fig. 89. orographic apparatus to record the suc- 



cessive changes occurring during ferti- 

 lisation and cell-division. The author used (fig. 90) a Zeiss Microscope 

 and photographic apparatus, a prism being inserted between the ocular 

 and bellows. The correct focus was obtained by means of a mirror, 

 revolving 45°, placed in the box intervening between the bellows and 

 the kinematograph ; the image being thrown on a round glass disk. 

 When the egg was ripe for division, the mirror was turned, the rays 

 from the Microscope being then directed on to the kinematograph film. 

 The progress of division was from time to time controlled by means 

 of the mirror. The kinematograph apparatus was the ordinary Lumiere's, 

 and was actuated by a clockwork mechanism which turned the crank 

 seven times a minute. The illuminant, an electric metallic film lamp, 



* Bull. Soc. Zool. de Geneve, 1908, p. 104. 



t Arch. Mikr. Anat. u. Entwickl., lxxiv. (1909) pp. 1-31 (2 pis. and 12 figs.). 



