126 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



Fig. 25. 



"Katsch's Large Microtome.* — In tliis instrument (Fig. 25), a 

 stand, similar to that of a sewing-machine, supports a tray, across 

 which, in a diagonal direction, a small ledge is fixed. This is inclined 



rather outwards, and on one end of 

 it the cutting knife rests, so as to 

 move steadily against the micro- 

 tome plate which rises a little above 

 the tray, and surrounds the pre- 

 paration. The plate itself is at 

 the end of a hollow cylinder fixed 

 to the tray, in which a massive 

 metal cylinder can be raised and 

 lowered by a screw underneath. 

 There are three knobs on the upper 

 part of this cylinder to fix the sub- 

 stance in which the preparation is 

 imbedded. 



When the latter is cooled (which 

 is done by pouring water into the 

 tray) the section can be made. 



A special advantage of this form 

 of instrument is that sections can 

 be cut under water, and that the 

 screw may be fixed by means of a 

 small click to the ^^oVff ^''^- ^^ 

 turning the screw the click is caught at every 3-^^575 mm., and gives 

 an audible signal. 



Cox's " Simple Section-cutter for Beginners."! — In this, economy 

 and simplicity have been carried to at least their furthest practicable 

 limits, as the basis of the instrument is a sewing-machine cotton-reel, 

 and a Perry's music binder. The cost does not exceed 2 or 3 pence. 



Cutting Sections of very small Objects. J — H. Strasser adds 

 from 3 to 4 parts of tallow to the imbedding mixture recommended by 

 Kleinenberg (spermaceti 4 parts, castor-oil 1 part), and in order to be 

 able conveniently to arrange very small objects for cutting sections in 

 any required position, he places them in the mass while this is still 

 warm, between plates of mica ; the temperature must never exceed 

 45° C. After cooling the mica plates may be readily separated from 

 the mass, which has the form of a thin sheet, and contains the object ; 

 it may be then fixed with heated pins in the desired position upon a 

 block of a substance not easily melted. 



Mounting in Balsam.§ — Dr. C. Seiler, in a paper contrasting 

 glycerine and balsam as mounting materials, gives the following as 

 a desirable modification of the old process of mounting in various 



* Thanhofifer's ' Das Mlkroskop und seine An wendirag,' 1880, pp. 96-7(1 fig.), 

 t Ann. Rep. Postal Micr. Soc, 1881, pp. 12-13 (1 fig.) 



X Morphol. Jahrbuch, v. (1879) p. 243. Cf. Zool. Jahresber. Naples, i. (for 

 1879) p. 35, 



§ Proc. Araer. Soc. Micr., 1881, pp. 60-2. 



