VALENTIN'S DISSECTING KNIFE. 75 



Tim improved Valentin's Knife. — For making fine sections of laroe 

 substances, or those soft in structure, such as the liver, spleen, and 

 kidney, the double-hladed knife, the invention of Professor Valentin, 

 may be used with advantage. An improved construction of this knife 

 by Professor Quekett is represented in fig. 58. It consists of two 

 blades, one of which is prolonged by a flat piece of steel to form a 

 handle, aad has two pieces of wood riveted to it for the purpose of its 



fig. 58. 



being held more steadily ; to this blade another one is attached by a 

 screw ; this last is also lengthened by a shorter piece of steel, and both 

 it and the preceding have slits cut out in them exactly opposite to each 

 other, up and down which slit a rivet with two heads is made to slide, 

 for the purpose either of allowing the blades to be widely separated or 

 brought so closely together as to touch. One head of this rivet, being 

 smaller than the hole in the end of the slit, can be drawn through it ; 

 so that the blade seen in the front of the figure may be turned away 

 from the other in order to be sharpened, or allow of the section made 

 by it being taken away from between the blades. The blades are so 

 constructed that their opposed surfaces are either flat or very slightly 

 concave, so that they may fit accurately to each other, which is efiected 

 more completely by a steadying-pin, seen at the base of the front blade. 

 When the instrument is required to be used, the thickness of the section 

 about to be made will depend upon the distance the blades are apart : 

 and this is regulated by sliding up or down the rivet, as the blades, by 

 their own elasticity, will always spring open and keep the rivet in 

 place ; a cut is then to be made by it, as with an ordinary knife, and 

 the part cut will be found between the blades, from which it may be 

 separated either by opening them as wide as possible by the rivet, or 

 by turning them apart in the manner before described, and floating the 

 section out in water. 



Disaecting Scissors. — In addition to the forceps and knives, scissors 

 will be necessary for the purposes of dissection : of these the most useful 



