SILVER NITRATE. 139 



The HOGGANS (Journ. ofAnat. and Physiol., xv, 1881, p. 477) 

 take, for lymphatics, a 1 per cent, solution. 



TOURNEUX and HERMANN (ROBIN'S Journal de I'Anat., 1876, 

 p. 200), in their fine studies on the epithelia of Invertebrates, 

 employed a solution of 3'1000 strength, and in some cases 

 weaker solutions. The tissues were allowed to remain in the 

 silver-bath for one hour, and were washed out with alcohol of 

 36 strength. 



HOYER (Arch. f. mik. Anat. t 1876, p. 649) takes a solution 

 of nitrate of silver of known strength, and adds ammonia. to 

 it until the precipitate that is formed just redissolves, then 

 dilutes the solution until it contains from 0'75 to 0'50 per 

 cent, of the salt. 



This ammonia-nitrate solution is intended principally for the 

 impregnation of the endothelium of vessels by injection, but 

 can also be used for the impregnation of membranes by pour- 

 ing on. It has the advantage of impregnating absolutely 

 nothing but endothelium or epithelium ; connective tissue is 

 not affected by it. It is also said to give a sharper localisation 

 of the stain than the ordinary solutions. 



DEKHUYSEN (Anat. Anz., iv, 1889, No. 25, p. 789 ; Zeit. f. 

 wiss. Mik.j vii, 3, 1890, p. 351) has applied to tissues of 

 terrestrial animals the method of HARMER for marine animals 

 (see Tselow, 217). He -washes a portion of mesentery of a 

 frog in a 1*3 per cent, solution of nitrate of potash, and 

 brings it for^rom three to six minutes into a 0'25 per cent, 

 solution of silver nitrate containing 3 per cent, of nitric acid. 

 After that time it is brought into pure 3 per cent, nitric acid, 

 thence after a few minutes into 96 per cent, alcohol, and then 

 into clove oil, in which it is reduced in diffused light in a few 

 minutes. The method is stated to have the advantage of 

 giving an excellent fixation of tissues, and of allowing a good 

 nuclear after-stain with haematoxylin, safranin, or methyl 

 green. 



ALFEROW (Arch, de Physiol., 1874; Laboratoire d'histologie 

 du College de France, 1874, p. 258; DUVAL, Precis, p. 230) 

 recommends the soluble silver salts of organic acids, viz. the 

 picrate, lactate, acetate, and citrate, as giving better results 

 than the nitrate. He employs them in solutions of 1*800, and 

 adds to the solution employed for staining a small quantity of 

 the acid of the salt taken (10 to 15 drops of a concentrated 



