VALENTIN S KNIFE. 



201 



covered with white wax, and then immerse it in the water- 

 troucrh ; the more delicate the structure, the sooner after 

 death should it be examined, especially animal tissues. 

 With some vegetable structures, the dissection should be 

 carried on under water. The sepa- 

 ration of the woody and vascular 

 tissues, and the spiral vessels, is best 

 effected by maceration and tearing 

 with fine needles. 



Valentin' s Knife. — ¥or making fine 

 sections of large substances, or those 

 soft in structure, such as the liver, 

 spleen, kidney, &c., the double-bladed 

 knife, the invention of Professor 

 Valentin, may be used with advan- 

 tage. An improved construction of 

 this knife, by the late Mr. John 

 Quekett, is represented in fig. 129.^ 

 It consists of two blades, one of 

 which is prolonged by a flat piece of 

 steel to form a handle, and having 

 two pieces of wood riveted to it, for 

 the purpose of its being held more \^^i ^^ 



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 slots cut out in them exactly 

 opposite to each other, up and down 

 which slot 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 to- 

 gether as to touch. One head of this 

 rivet, being smaller than the hole in 

 the end of the slot, 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, 



(I) Another f cim of this instrument is constructed by Mr. Matthews, the 

 blades being made with a convex instead of a straight edge, their distances from 

 each other being regulated by a milled-head screw, and their separation fot 

 cleaning being more readily accomplished. 



129. 



