206 On Cutting Sections of Animal Tissues 



finely-powdered salt, into a large vessel, mixing the two ingredients 

 thoroughly after each addition. The object, which must be small, 

 should be cut to an oblong form, and placed on a flat cork, much 

 wider than itself. It must be pinned to this cork at the end 

 opposite that from which the sections are to be cut. In the case 

 of a membrane the object must be folded, and fixed in the same way. 

 The whole is then placed in a platinum crucible, which has been 

 previously plunged into the freezing mixture. The crucible must 

 be at once covered, and a little of the freezing mixture placed on 

 the top of it. The section knife, which must be sharp, is cooled by 

 laying it on ice. As soon as it is ascertained by exploration with a 

 needle that the preparation is firm enough, the knife is handed to 

 an assistant, who wipes it, and holds it in readiness. The cork is 

 then taken out with the forceps, and seized by the fingers of the 

 left hand in such a way that they do not come into contact with 

 the preparation. A succession of sections having been rapidly made, 

 the number varying with the skill of the operator, the cork is 

 replaced in the crucible." This method, perhaps giving very satis- 

 factory results in dexterous hands, seems to be excessively tedious, 

 awkward, and rather primitive, in comparison with that to be next 

 described. 



(2.) The best way to obtain sections of fresh, hardened, or 

 softened tissues for immediate examination or further treatment, is, 

 undoubtedly, by freezing in the refrigerating microtome. I refer 

 to Mr. McCarthy's modification of Professor Rutherford's micro- 

 tome, made by Khrone and Sesseman, of Whitechapel Road. It 

 consists essentially of a brass plate having a hole in the centre ; to 

 the under surface a tube is fixed whose bore corresponds to, and is 

 continuous with, the hole ; a thin ping is accurately packed in the 

 tube, capable of being moved up and down by means of a graduated 

 screw : external to the tube is an oblong box, through the bottom 

 of which the screw passes into the tube. A small tap communi- 

 cates with the interior of the box to carry off water, if necessary, as 

 produced by the ice. The plate rests on, and occupies about the 

 middle fourth of two sides of the outer box. The whole is capable 

 of being securely fastened to any table by a second screw. The 

 machine is made of brass, and the sides are padded externally with 

 leather. 



The machine is first fastened to a table, a large square piece of 

 flannel being interposed between them, the tap turned on, and the 

 plug forced to the bottom of the tube, after displacing the graduated 

 screw. The pieces of tissues — I say " pieces," because two or more 

 different portions may be cut at the same time, if it be possible to 

 distinguish the sections by the shape or colour from each other ; 

 e.g. lung and intestine may be readily distinguished by their shape, 

 and easily separated after being cut into sections of extreme 



