12 PRACTICAL WORK CHAP. 



HINTS ON DISSECTION AND DRAWING 



Instruments and other Requisites for Dissection. 1 In 

 order to carry out the dissection of the frog and other 

 animals successfully it is necessary to be provided with 

 proper tools. The most important are 



i. Three or four sharp dissecting knives, or scalpels, of 

 different sizes. 



2. A large and a small pair of straight dissecting-forceps ; 

 the small pair should have a peg on one leg fitting into a 

 hole on the other, to prevent the points crossing; the 

 points should be roughened. 



3. A large and a small, fine-pointed pair of dissecting 

 scissors ; the small pair for the more delicate work, and the 

 large pair for coarser work and for cutting through bones. 

 For the latter purpose a pair of bone-forceps is useful, but is 

 not necessary in the case of such a small animal as the frog. 



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



5. Three or four probes ; a seeker or knitting needle, or a 

 thin slip of whalebone will answer for some purposes, but 

 the most generally useful form of probe is made by sticking 

 the end of a hog's bristle into melted sealing wax, and 

 immediately withdrawing it so as to affix a little knob or 

 guard. 



6. An anatomical blowpipe, or, failing this, a piece of 

 glass-tubing, 6 or 8 inches long, with one end drawn out in 

 the flame until it is not more than ^th to o^th of an inch 

 in diameter. 



7. An ordinary " medicine-dropper," or " feeder " of a 

 self-feeding pen (see Fig. 25), made of a piece of glass-tubing 

 about three inches long, drawn out in the flame at one end, 

 and thickened at the other so as to form a collar, over which 

 an india-rubber cap an ordinary non-perforated teat is 

 fixed. This is useful for washing fine dissections, as well as 

 for injecting. 



8. A disseciing-dish. Get a common pie-dish, about 6 or 

 8 inches long, with rather low sides. Cut out a piece of 

 cork-carpet or thick linoleum the size of the bottom of the 

 dish, and a piece of sheet-lead of the same size, and fasten 

 the two together by three or four ties of copper wire or 



1 A suitable box of dissecting instruments can be bought from 

 most scientific instrument makers for about 135.-^!. (For further 

 apparatus required in connection with injection and micro- 

 scopical work, see pp. 99, 119, and 135.) 



