THE PREPABATION OF ANIMAL TISSUES. 59 



posterior (ventral) surface of a rabbit or guinea- 

 pig, immediately after death by bleeding, thus : 

 Ligature the gullet and the posterior vena cava, 

 then remove all the abdominal viscera. Tie up by 

 the hind legs, then with a brush dipped in distilled 

 water brush away all the epithelium covering the 

 centrum tendinuin of the diaphragm. "Wash silver 

 solution over it, and treat as already explained. 

 This silvers the endothelia lining the lymphatics. 



Chloride of Gold. 



This salt is sold in small tubes containing 15 

 grains. A 2 per cent, solution is to be made with 

 very pure distilled water, and kept in a black 

 bottle, like the silver solution. The operator must 

 also provide himself with formic acid and two or 

 three fresh lemons. 



Development of Capillaries. Snip off the tail of a 

 half-grown tadpole, place it in a watch glass, and 

 squeeze the juice from a fresh lemon over it, and 

 let it remain immersed for five or ten minutes ; 

 wash it in distilled water to remove all the juice ; 

 then steep it for half-an-hour in a 1 per cent, solu- 

 tion. Wash away the surplus gold, then place in 

 a mixture of one part of formic acid and three 

 parts of water for twenty-four hours in a cool place 

 and away from the light. The gold chloride will 

 then be reduced. 



The following are to be treated in exactly the 

 same manner : 



A whole Cornea. That of a pig, dog, or cat, to 

 show the nerves of the cornea, also the cornea 

 corpuscles. 



