104 METHODS. 



it has been hardened in any aqueous solution, e. g., chromic 

 acid or bichromate of potash, it must be first steeped in com- 

 mon alcohol. According to the size of the bit, a little box or 

 case, of paper or any suitable material, such, for example, as 

 zinc foil, must be made, so that it will hold the fused mixture. 

 When paper is used, the sides are joined with gum or paste, 

 or are merely pinned together. The box should be about half 

 as long again as the object used. When ready, it is filled with 

 the fused wax-mass to a depth sufficient to cover the object. 

 As soon as the mass begins to solidify at the sides, the bit is 

 introduced as follows: A needle is stuck slightly into the 

 end opposite to that from which sections are to be cut, and 

 the bit is plunged into the mass with its long diameter hori- 

 zontal, and in such a position that the end furthest from the 

 needle is near, but not in contact with, the side of the box, 

 and, consequently, the other end is at a considerable distance 

 from the side. In this way, although the whole is surrounded 

 with the wax mass, there is a greater thickness around the end 

 into which the needle is stuck, so that the whole can be se- 

 curely and conveniently held. The solidification can be accel- 

 erated by immersion in water or alcohol. If the portions of 

 tissue are compact enough, it is possible to perforate the bit 

 with a very slender needle, the point of which is stuck into the 

 table or cork on which the box rests; by this means the ope- 

 rator is saved the trouble of holding the needle till the wax- 

 mixture solidifies. In finally withdrawing the needle, the 

 greatest care must be taken to give it a twisting motion, as 

 otherwise, especially if the object is thin, it is apt to be dis- 

 placed. If the object contains a cavity communicating with 

 the surface by a single opening (<?. g., the cochlea), it is neces- 

 sary fii'st to fill the cavity with the mass : this is done either 

 by placing it in vacuo, or by making an additional opening. 

 If a thin membrane is to be embedded, of such tenuity that a 

 needle could not be introduced without danger of destroying 

 it, the following methods may be used : (1) A box is half 

 filled with the mass, and then, as soon as it begins to solidify, 

 the membrane is applied to the half-solid surface, in such a 

 position as is most suitable with reference to the direction in 

 which the section is to be made. The box is then filled with 

 a thoroughly fused mass, care being taken that it is not too 

 hot. (2) The fused mass is allowed to drop on an object-glass 

 or a thin flat piece of cork, so as to form a layer thick enough 

 to serve as a basis for the object, which is then laid upon it 

 and covered with an additional layer of wax-mass. If an 

 object-glass is used, it must be first covered with turpentine, 

 otherwise it will be difficult to remove the solidified mass from 

 it. In all cases the surface of the object must be nearly 



