52 i SUMMARY OF CURRENT RESEARCHES RELATING TO 



of 1 in. or 1^ in., if placed against them, will be accurately centered ; and the 

 screws are also so arranged that when it is desired to use the turntable as a non- 

 centerino- one, the screws may be depressed below the surface of the table.] 



Trans. Edinburgh Naturalists' Field Club, I. (1885-6) pp. 333-4, 

 James, F. L.— Microscopical Technology. [XV. Finishing the slide.] 



Sf. Lmis Med. and Surg. Joum., LII. (1887) pp. 36-41 (2 figs.). 



(6) Miscellaneous. 

 Belireiis's Tables for Microscopists.*— Dr. W. Belirens has here col- 

 lected a series of very useful tables for microscopists and others. They 

 comprise the comparison of the metric and English scales of lengths and 

 weights as well as of thermometer scales ; various tables of specific weights, 

 refractive indices and dispersive powers ; a numerical aperture table ; and 

 tables of hardening, fixing, imbedding, clearing, staining, and other media. 

 There are fifty-four tables in all. 



Method for Exhibiting- Semi-Microscopical Objects.f— Herr F. Hil- 

 gendorf, after alluding to the difficulty of studying carefully small objects 

 in museums, remarks that the exhibition of a large number of Micro- 

 scopes is frustrated by the great expense and by the clumsiness of the 

 public. The chief difficulty which arises from the difierences of vision in 

 diiferent individuals, namely, constant alteration of focus, can be obviated 

 by an ingenious contrivance such as has been employed by Dr. Zenker in 

 the microscopical aquarium. This consists in every observer correcting 

 his focus by means of a suitably chosen lens placed before the ocular, and 

 with this lens traversing the whole series of Microscopes, each of which 

 has been adjusted to the same focus. 



The objects should be placed in a frame, the sides of w-hich should bo 

 made of glass, and this frame, inclosing the specimens, set up in a vertical 

 position close to a window. A hand-lens which allows a sufficient space 

 between the glass and the eye for the nose and hand, would be necessary for 

 examining purposes. The side plates of the frame must of course be made 

 of smooth, clear, and not too thick glass. It will be found that at least 

 100 different semi-microscopical objects can be exhibited in each frame. 

 As these frames stand only before the lower part of the window, darkening 

 of the room need not be feared. If it be desirable to increase the number 

 of preparations for examination, a contrivance adopted in some museums 

 is recommended. This is an upright column around which are fixed a 

 certain number of glass frames in such a manner that the latter can be 

 made to revolve round the vertical axis. 



The author enumerates certain objects suitable for such exhibition cases. 

 These, beginning with the Protozoa, are chiefly Invertebrata, but many 

 parts of vertebrates, such as fish-scales, otoliths, sclerotic rings, feathers, 

 hairs, &c., are suggested. 



Drying and Heating Apparatus for the Histological Laboratory.! — 

 Herr V. Meyer has had constructed an apparatus which, though intended 

 for chemical work, may be found useful in the histological laboratory, 

 instead of the incubator or hot chamber. In the latter the constancy 

 of the temperature is maintained by means of the thermo-regulator. 

 Meyer's apparatus dispenses with such adjuncts, because the temperature 



♦ Behrens, W., ' Tabellen zum Gebrauch bei mikroakopischen Arbeiten.' (Tables for 

 use in Microscopical Work.) 76 pp., 8vo, Braunschweig, 1887. 



t SB. Gesell. Naturf. Freunde, 18S5, pp. 13-6. 



X Ber. Deutsch. Chem. Gesell., xviii. No. 17, p. 2999. Cf. Zeitscbr. f. Wise. Mikr., iii. 

 (1886) p. 74 (I fig). 



