SILVER NITRATE. 139 



The HOGGANS (Journ. of Anal, and PhysioL, xv, 1881, p. 477) 

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



TOURNEUX and HERMANN (ROBIN'S Journal de VAnat., 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., 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 ammonio-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., vii, 3, 1890, p. 351) has applied to tissues of 

 terrestrial animals the method of HARMER for marine animals 

 (see below, 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 from 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 



