468 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



Culture Glass for examining Micro-organisms.* — The glass invented 

 by Dr. F, Lipcz consists of a flat and a round part. The former is for the 

 reception of the nutrient medium; the latter for the cotton-wool plug. 



Fig. 108. 



(1 



X" 



Fig. 109. 



Fig. 110. 



Fig. 108 shows the instrument in section ; fig. 109 from the surface. One- 

 third the natural size. 



The nutrient modium is only spread in a thin layer on the lower surface 

 of the glass. The advantages claimed for this glass over the ordinary plate 

 method arc : (1) The simplicity of its application, for it is a storehouse as 

 well as a laboratory ; (2) its certainty of preventing ingress of extraneous 

 organisms, &c ; (3) it allows the colonies to be examined with low powers, 

 and to be extracted for examination if need be ; (4) it allows the action of 

 certain gases in the organisms to be observed with facility — e.g. CO^ can be 

 poured in and H gas poured up, according to the position of the aperture. 



ScMeJfferdecker's Apparatus for Marking Microscopical Objects.f — 

 Dr. P. Schiefierdecker's apparatus (fig. 110) is essentially a diamond point 

 for scratching circles on the cover-glass, so that any 

 particular spot can be easily found. 



It consists of the screw-head A, to which is 

 united the piece B, of unequal length and diameter 

 at a and c. At h are a few threads for working in 

 the female screw &', which supports the revolving 

 cylinder C, but without interfering with its move- 

 ments. C is united to a second revolving cylinder 

 D by means of the screw m. A linear aperture at 

 ■m allows free up and down movement of the parts 

 from D to Ji. The horizontal slide i is moved by 

 the screw / and the spring g. At the end of h is 

 a diamond point. The apparatus is screwed to the 

 body-tube in place of the objective, and h is moved 

 out excentrically to the desired extent, and a circle 

 is scratched on the cover-glass by turning the 

 raised rim d round through 360'^. By this means 

 circles of 0*25 to 0*20 mm. diameter can be 

 described. Of course it is necessary that the cover- 

 glass should be firmly fixed. 



Microscopic Measurement of Indices of Refraction and Axial Angle 

 of Minerals. — M. E. Bertrand + is able to observe the optic axes in a 

 mineral of which the true axial angle is 14.5°, by increasing the aperture of 

 the condenser and objective, and using a strongly refracting immersion 

 liquid. For this purpose, the condenser consists of throe lenses, which 

 are respectively hemispherical of 5 mm. radius, 5 mm. thick with 12 mm. 

 radius, and 19 mm. diameter with 60 mm. focal length ; the objective 

 consists of 3 lenses which are respectively hemispherical of 1^ mm. radius, 



* Ccntralbl. f. Bacteriol. u. Parasitenk., i. (1887) pp. 401-2 (2 figs.). 



t Zeitschr. f. Wise. Mikr., iii. (1886) pp. 4G1-4 (1 fig.). 



X Bull. Soc. Mill, dc France, viii. (1885) pp. 29-31, 377-83. 



