2 ON DISSECTION. 



5. A pair of the finest sewing needles, mounted in handles : 

 only about a quarter of an inch of the needle should 2^1'oject. 

 They are used for teasing histological preparations. 



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

 bent at an angle half an inch from the end. 



7. A metal blow ])ij)G : and a glass cannula with india-rubber 

 cap. 



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

 a handle, and giving wdien combined a magnifying power of at 

 least six diameters. 



9. Slides and coverslips, for mounting microscopical speci- 

 mens. The coverslips should be the thinnest sold (No. 1). 



10. A blank note book, for drawing in ; an HB pencil, and a 

 piece of india-rubber. 



11. A cheap pair of compasses, for measuring the dissections. 



III.-ON DISSECTION. 



The object of dissection is to separate the several parts and 

 organs from one another, so as to define their boundaries and 

 display clearly their mutual relations. Dissection consists 

 mainly in removing the " connective tissue " which binds the 

 several parts together. 



The following rules should be carefully attended to : — 



1. Pin down the animal firmly to the dissecting board. 

 Never attempt to dissect a specimen that is not so fixed. 



2. In pinning out a dissection stick the pins in, not vertically, 

 but obliquely, so that their heads do not get in the way or 

 obscure the dissection. 



3. Never cut away anything until you are quite certain what 

 it is you are removing. 



4. Put the part you are dissecting slightly on the stretch ; 

 e.g., when dissecting the bloodvessels or nerves of the throat, 

 distend it by passing a small roll of paper or the handle of a 

 seeker down the oesophagus ; or when dissecting the muscles of 

 the leg, pin out the leg in such a position as to stretch the 

 muscles you are cleaning. 



5. In cleaning bloodvessels or nerves always dissect along 

 them and not across them ; and avoid laying hold of them with 

 the forceps. Similarly when cleaning muscles, dissect along 

 their fibres and not across them. 



