344 SUMMARY OF CURRENT RESEARCHES RELATINQ TO 



given point of fusion. Pieces of paraffin are placed in the funnel 

 and heated to the point desired. The liquid which runs out of the 

 funnel is collected, and will be found to melt at the temperature 

 indicated at the moment of filtering. 



Dr. Francotto also suggests that the funnel A B may replace the 

 vessel K in his vacuum apparatus, ante p. 149, one of the apertures 

 being used for the barometer tube and the other communicating with 

 the vessel with the paraffin. The funnel is cooled by passing water 

 through it. 



Parabolic Mirror for Correction of too hard or too soft Paraffin.* 

 — Prof. H. Fol suggests that if, after the cutting has begun, the 

 paraffin is found to be too hard, it may be softened by the following 

 simple and ingenious expedient : — 



A lamp provided with a parabolic reflector is set up near the 

 microtome in such a position that the heat-rays of the flame are 

 thrown by the reflector on to the imbedded object. The right 

 temperature is obtained by adjusting the distance of the lamp. If, 

 on the contrary, the paraffin be found too soft, it may be hardened by 

 exposing it to the cooling influence of a lump of ice placed in the 

 focus of a similar reflector. 



Beck's Universal Microtome. — In this microtome (fig. 84) 

 Messrs. Beck have very ingeniously combined in one instrument the 

 means for cutting sections of soft tissues under all the varied con- 

 ditions required in this class of work : — Istly, for cutting consecutive 

 sections, which are carried oflf the knife by a continuous ribbon. 

 2ndly, for cutting sections when frozen by ether. 3rdly, for cutting 

 unimbedded sections. 4thly, for cutting sections with a long diagonal 

 knife. Special arrangements are made for freezing by ice, or for cut- 

 ting substances under spirits if desired. The Schanze form has been 

 adopted as the basis of the instrument, the main frame consisting of 

 a solid iron base and an upright. The latter carries on one side a 

 carefully planed out V-shaped groove A, on which a heavy brass 

 block B, to which the knife is attached, slides with great accuracy 

 and ease. To this block and behind the knife the apparatus carrying 

 the revolving ribbon C is clamped. This is readily removed when 

 desired. 



On the other side of the upright is a vertical slide working in a 

 dovetail, and can-ying the mechanism to which the object-holder is 

 attached. The various modes of holding the object are shown at — D 

 when the object is imbedded in paraffin for ribbon cutting ; E when 

 the object is frozen by ether ; and F when it is clamped in the holder. 

 The socket into which the object-holder fits has rectangular move- 

 ments controlled by the two thumb-screws, so that the object-holder 

 can be placed in any position. The whole is moved up and down by 

 the lever seen in front of the upright, which brings it in contact with 

 the top of a highly polished steel screw of very delicate construction, 

 upon which it rests. To this screw is attached a large ratchet 



♦ Fol, H., 'Lehrbuch d. vergl. Mikr. Anatomie,' 1884, p. 123. Cf. Lee'B 

 Microtomists' Vade Mecum, 1885. p. 401. 



