METALLIC STAINS 203 



The Hertwigs take, for marine animals, a 1 per cent, solution 

 {Jeii. Zeit. Naiurk., xvi, p}). 31. *3 and 324.). 



The HoGGANS {Journ. of Anat. and Physiol., xv, 1881, p. 477) 

 take for lymphatics a 1 per cent, solution. 



TouRNEux and Herrmann (Robin's Journal de VAnat., 187G, 

 p. 200) took for the epithclia of Invertebrates 3 : 1000, and in 

 some cases weaker solutions — for one hour, washing out with 

 alcohol of 90 per cent. 



HoYER {Arch. mik. Anat., 1867, p. 649) takes a solution of 

 nitrate of silver, and adds anmionia 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 has the advantage of impregnating absolutely 

 nothing but endothelium or epithelium ; connective tissue is not 

 affected by it. 



Ranvier's injection-mass for impregnating endothelium is 

 given under " Injection." 



Dekhuyzen {Anat. Anz., iv, 1889, No. 25, p. 789) has applied 

 to terrestrial animals the method of Harmer for marine animals 

 (§ 395). For details see previous editions. 



Regaud {Journ. Anat. et Phys., xxx, 1894, p. 719) recom- 

 mends for the study of lymphatics a process devised by Renaut, 

 for the details of which see also previous editions. 



392. Other Salts of Silver. Alferow {Arch. Phys., i, 1874, p. 694) 

 employs the picrate, lactate, acetate, and citrate, in solution of 1 : 800, 

 and adds a small quantity of the acid of the salt taken (10 to 15 drops of 

 a concentrated solution of the acid to 800 c.c. of the solution of the salt). 

 This decomposes the precipitates formed by the action of the silver 

 salt on the chlorides, carbonates, and other substances existing in the 

 tissues. 



Regaud and Dubreuil {C.R. Ass. Anat., 5 Sess. 1903, p. 122) take a 

 fresh solution of protargol or a mixture of equal parts of 1 per cent, 

 protargol and 1 per cent, osmic acid, avoiding precipitates. 



393. Silver Nitrate : Reduction. Reduction may be effected in 

 media other than distilled water. 



V. Recklinghausen washed his preparations in salt solution 

 before exposing them to the light in distilled water {Arch. path. 

 Anat., xix, p. 451). Physiological salt solution (0-75 per cent.) 

 is commonly used for these washings. 



MtJLLER {Arch. f. path. Anal., xxxi, p. 110), after impregnation 

 by immersion for two or three minutes in a 1 per cent, solution 

 of nitrate of silver in the dark, adds to the solution a small quantity 

 of 1 per cent, solution of iodide of silver (dissolved by the aid of a 

 little iodide of potassium). After being agitated in this mixture 

 the preparations are washed with distilled water, and exposed 

 to the light for two days in a 1 per cent, solution of nitrate of silver 

 (see also Gierke, in Zeit. wiss. Mik., i, 1884, p. 396). 



RouGET {Arch, de Physiol, 1873, p. 603) reduces in glycerin ; 



