21)8 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



Ceresine and Vaseline for Imbedding.* — Dr. M. Scliulgin prefers 

 instead of pure paraffin a mixture of that substance with ceresine and 

 vaseline. The paraffin should melt at 55°, and to it add at discretion 

 ceresine, the density of which is considerably greater than that of the 

 former. Ceresine is like wax, but harder and tougher, properties 

 which make it very valuable as an imbedding substance. The mixture 

 is tolerably hard, but that does not matter, as it is tough at the same 

 time. If a soft mass is wanted vaseline must be added at discretion. 

 Its special property is that it is not greasy but soft and tough. 



Paul's Modification of Williams' Freezing Microtome.t— 

 Mr. F. A. Paul modifies this instrument by making the inner 

 cylinder movable while the outer one is fixed. The inner cylinder, 

 carrying the frozen mass, is attached to the short arm of a lever 

 below, the long arm of which is actuated by a fine screw, which 

 extends above the upper plate, and is fitted not with a milled head 

 but with a toothed wheel. The frame to which the knife is attached 

 works on a pivot in the upper plate, and rests by two rounded legs on 

 the plate as it moves over it. A hinge in the frame allows the razor 

 to be lifted clear of the imbedded material on the return movement. 

 An adjustable catch on the razor-frame turns the toothed wheel and 

 its screw through a given part of a revolution, so as to elevate the 

 mass by any desired amount at each cut of the knife. 



Thoma's Sliding Microtome (Imbedding Methods). — Dr. E. 

 Thoma, Extraordinary Professor of Pathological Anatomy at the Uni- 

 versity of Heidelberg, has been good enough to write us the following 

 description (in English) of his instrument, which has acquired con- 

 siderable reputation both on the Continent and in England.J He 

 adds also remarks on its use. 



The microtome (fig. 51) consists of a stand of cast-iron, on 



Fig. 51. 



Thoma's Microtome. — n, carrier for the knife ; h, carrier for the object ; 

 c, micrometer-screw for fine adjiislmeut. 



which slide two carriers. The large knife is attached to one of these 

 a, which slides horizontally. Tlie second h holds the specimen to 



* Zool. Anzeig., vi. (1883) pp. 21-2. 



t Prnc. Amer. Soc. Micr., .5th Ann. Meeting, 1882, pp. 283-4. 

 X A brief description without figs, appeared in Virchow's Archiv, Ixxxiv. 

 (1881) pp. 189-91. 



