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 success- 

 fully it is necessary to be provided with proper tools. The most 

 important are 



1 . 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 T Vth to ^jth 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 dissecting 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 strong thread. Place this in the dish with the lead 



1 A suitable box of dissecting instruments can be bought from most 

 scientific instrument makers for about i. (For further apparatus re- 

 quired in connection with injection and microscopical work, see pp. 99, 

 119, and 135.) 



