318 APPENDIX 



for 5 to 10 minutes in osmic acid, well washed, and exposed 

 to light. 



Instead of silver nitrate, the following are sometimes used : 

 (a) silver lactate, acetate and citrate ; 1 drop of 1 p.c. solution of 

 the acid being added to 1 c.c. of the -5 p.c. solution of the salt ; 

 (6) ammonia is added drop by drop to 1 p.c. silver nitrate until 

 the first formed precipitate is re-dissolved ; distilled water is 

 then added to make a -5 or -25 p.c. solution of silver nitrate; 

 (c) 1 p.c. largin or other organic silver compound. 



The nuclei of a tissue which has been treated with nitrate of 

 silver, provided the treatment has not been too long, may be 

 stained with any nuclear stain. 



Nitrate of silver is sometimes applied in the solid, as lunar caustic, 

 but their results are not very satisfactory. 



References to the use of nitrate of silver in the text, besides 

 those mentioned above, are : epithelium of vein, p. 134 ; injection 

 of blood vessels generally, p. 136, of spleen, p. 154, of kidney, 

 p. 200 ; serous membrane, lymphatics, and diaphragm, pp. 

 143_145. 



GOLD CHLORIDE. 



The tissue is usually treated with gold chloride immediately 

 after the death of the animal, but according to Drasch it is best 

 to leave the animal for 12 to 24 hours after death at about 3 C. 

 (method i. 6, Auerbach's plexus, papilla foliata). 



The piece of tissue should not be larger than necessary, since 

 gold chloride does not penetrate well ; it should be transferred 

 from one fluid to another with a small brush or a glass rod. 



i. The tissue is placed in -5 to 1 p.c. gold chloride for 

 20 minutes to an hour and washed well in water. It is then 

 placed in 



a. water acidulated with acetic acid (about 1 drop of acetic 

 acid to 50 c.c. of water), and exposed to light. 



The success of this and of other methods in which the tissue 

 is exposed to the light depends upon exposure to bright sunlight. 

 On cloudy days, the electric light should be used. The method 

 gives good results with the cornea (cp. pp. 72, 210). 



