ON DISSECTION xvii 



should be taken to see that they cut quite up to the points of 

 the blades. 



4. A pair of bone-forceps or very stout scissors, for cutting 

 bone and other hard substances. 



5. A pair of stout needles, firmly mounted in handles. 



6. A pair of the finest sewing-needles, mounted in handles. 

 Only about a quarter of an inch of the needle should project. 

 They are used for teasing histological preparations. 



7. A seeker, i.e. a blunt needle mounted in a handle, and 

 with the end bent at an angle. 



8. A pocket-lens, containing two or three lenses mounted 

 in a handle, and giving when combined a magnifying power 

 of at least six diameters. 



9. A razor, and some means for keeping it sharp. 



For the dissection of the larger animals, as the dog-fish or 

 rabbit, an ordinary deal board, about two feet long by a foot 

 and a half wide, may be used : to this the animal should be 

 fastened by pins, those with large round heads being especially 

 convenient. 



Smaller animals, and special parts of larger ones, should 

 be dissected under water, which supports the parts and greatly 

 facilitates the operation. For this purpose an ordinary white 

 pie-dish with sloping sides is very suitable, the bottom being 

 fitted with a soft deal board weighted with lead, or a sheet of 

 cork cemented in with marine glue. A similar but smaller 

 dish may be used for dissecting under spirit. 



Animals, such as the cockroach, which are difficult to fix 

 with pins may be cemented down with melted wax, or they 

 may be half imbedded in a plate of paraffin, and the plate 

 then fixed down with pins in the dissecting-dish. 



For fine work a dissecting microscope affords great assist- 

 ance. The pocket-lens may readily be turned into one by 

 fitting one end of an ordinary wine-cork into the handle or 

 case of the lens, and passing a stout pin transversely through 

 the other end. The pin should be stuck upright into the 

 dissecting-board, with the lens over the part to be dissected : 

 focussing is effected by sliding the cork up and down the 

 pin. 



a 



