202 



THE MICROSCOPE. 



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, 

 that they may fit accurately to each other, which is effected 

 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 regu- 

 lated by sliding up and 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, ax\d the part cut will be found between 

 the blades, from which it may be separated either by open- 

 ing 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. 



Dissecting Scissors. In addition to the forceps and 

 knives, scissors will be necessary for the purposes of dissec- 

 tion: of these the most useful are shown in fig. 130. They 



Fig. 130. Dissecting Scissors. 



are made both straight and curved ; of the first kind, two 

 pairs will be required, one having the extremities broad, 

 and the other sharp-pointed ; if large dissections be under- 

 taken, a still stronger pair, with the extremities broad, 

 and made rough like a file, will be necessary. In dis- 

 secting under the microscope, the curved-pointed pair 

 shown at / are the most convenient. In all of these 

 instruments the points should fit accurately together : 

 sometimes those that are very sharp are apt to cross ; this 



