12 PRACTICAL WORK chap. 



HINTS ON DISSECTION 



Instruments and other Requisites for Dissection.'— in 



urder to carry out the dissection of tlie frog and oilier animals success- 

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

 important arc — 



1. Three i>r four sharp dissecting knives, or scalfch, of different sizes. 



2. A large and a small pair of straight dissecting foneps ; 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 fur the mcjre delicate work, and the large pair for coarser 

 W()rk and for cutting through Imnes. For the latter purpose a pair of 

 bo}ie-forceps is usehd, htit is nol necessary in the case of such a small 

 anintal as the frog. 



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



5. Three or [^^\\\ probes : a seeker lu knitting needle, or a thin slip 

 of whalebone w ill answer for some ptirposes, but the most generally 

 useful form of probe is made by sticking the end of a hog's bristle into 

 melted sealing-wax, and immediatel}' withdrawing it so as t(j affix a 

 little kn<.)b or guard. 



6. .'Vn atiatomical b/oupipe, 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 j^jjlh to Vjjth of an inch in diameter. 



7. An ordinary " mediiine-dropper," or " feeder" of a self-feeding pen 

 (see I'ig. 25), made of a piece of glass-tubing about 3 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 white pie-dish, about 6 or 8 

 inches long, with rather low sides. Cut out a piece of self-coloured 

 (brown) cork-carpet (jr thick linoleum the size of the liottom 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 



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

 scientific instrument makers for about /■!. (For further apparatus re- 

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

 119, and 135.) 



