2fi2 On Cutting Sections of Animal Tissues 



by means of a screw, the distance between the blades being regu- 

 lated by a second screw situated nearer tbe cutting portion of the 

 knife ; the blades are sharp at the point and wide at the base, so 

 that the cutting-edge slants downwards from the point. (2.) The 

 second form is that made by Mr. Matthews: the whole of this 

 knife is constructed of metal, the blades being continuous with the 

 handle ; they are short, and of equal breadth throughout ; the 

 cutting-edges are convex from point to base. An eye is attached 

 to one blade, and on the other — in a corresponding position — is a 

 longitudinal slot. In bringing the two portions of the knife 

 together, the eye passes through the slot, and they are secured in 

 position by sliding through the eye a spring-side thumb catch. 

 The distance between the blades is regulated by one or two screws. 

 (3.) The next form is that invented by Dr. Maddox, and manu- 

 factured by Mr. Baker, of High Holborn. It is a triple-bladed 

 section knife. The circumstances that led to this invention are 

 briefly described by him * as follows : — " I felt the want of some 

 method by which a double section might be cut, so as to present, 

 when removed, the opposite, but contiguous, surfaces of the part 

 through which the section had passed, and which with the ordinary 

 double-bladed knife is quite impossible." This knife overcomes 

 the disadvantage referred to ; at the same time by removal of one 

 of the outer blades it is convertible into an ordinary double-bladed 

 knife. 



In using these knives a difficulty will be experienced in regu- 

 lating the blades so that the interval between them may be equi- 

 distant throughout ; to render this more easily accomplished, Mr. 

 Hawksley, of Blenheim Street, has constructed an improvement on 

 Matthews' form. (4.) A spring is fixed between the two blades, 

 the distance being regulated by one screw, which has a graduated 

 milled head. By this arrangement parallelism is obtained with 

 facility ; it also has the additional advantage of indicating and 

 regulating the thickness of the section. 



The tissue to be operated on may be placed on cork, on the 

 wax tablet before referred to, or on leather, and held steadily 

 between the fingers and thumb of the left hand, or may be simply 

 retained between the fingers and thumb. The method devised by 

 Dr. Fenwick is remarkably good for membranous structures, e. g. 

 a portion of stomach is drawn around the thumb and held in posi- 

 tion by the fingers, the section being taken from that part covering 

 the thumb nail. The knife must be drawn by one continuous 

 stroke completely through the tissue, then the cutting-edge slightly 

 turned, so that the section may be severed from the surrounding 

 material. The section is now made, and is to be liberated by 

 opening the blades and gently agitating the knife in water, when 

 * Macldox, No. ], ' Monthly Microscopical Journal.' 



