71 i 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



Demonstration of Goblet-cells.* — For this purpose, Prof. W. 

 I'll mining recommends not only hematoxylin, which imparts a deep 

 blue or violet colour to tho contonts of tho goblet-cells in osmium 

 preparations, but also tho osmium mixture j* followed by staining 

 with gentian or safranin. The cell-contents then appear blue or 

 reddish brown, and stand out sharply even under low powers. 



Horizontal Lathe for Grinding and Polishing hard Objects.:}: — 

 Trof. A. Eternod has a grinding lathe by which hard objects aro 

 more easily prepared than by the ordinary grindstone or the dentist's 

 polishing lathe. Its main feature consists in being horizontal, and 

 it is hence very convenient to manipulate. 



It is made from the table of a sewing machine with its wheel and 

 pedal. The movement is communicated by means of an endless cat- 

 gut band running round a system of wheel pulleys. The details of 

 the machine will be understood from fig. 148. 



Prof. Eternod uses emery plates and Arkansas and Turkey stones 



Fig. 148. 



for grindstones. The Turkey stone is recommended on account of 

 the fineness of its grain for giving a perfect polish. Drainage of 

 the fluids employed for moistening the stones is effected by means of 

 a zinc plate provided with an overflow pipe. The plate also serves 

 to collect the sections as they leave tho grindstone, and prevents the 

 operator from being splashed. 



Various kinds of Slides. § — Dr. O. A. Wall describes the various 

 kinds of slides in use, commencing with the ordinary 3 in. by 1 in., 

 and the so-called " French " paper-covered slides 2 £ in. by 3/4 in. 



Sections of minerals are frequently mounted on special sizes of 

 slides, which are wider and shorter, or about 2 in, by 1^ in., so as to 

 allow a larger cover-glass to be used, and at the same time to be more 

 easily rotated with the stage of the Microscopes made for lithological 

 work, when the sections are to be examined with the polariscope. These 



* Zeitschr. f. Wiss. Mikr., ii. (1S85) p. 519. 



t Cf. Zeitschr. f. Wiss. Mikr., i. (1884) p. 340, and this Journal, v. (1885) 

 p. 554. 



% Zeitschr. f. Wiss. Mikr, ii. (1885) pp. 507-9 (3 figs.). 

 § St. Louis National Druggist, viii. (1886) pp. 24 and 39. 



