200 METALLIC STAINS [(IMPREGNATION METHODS). 



order to avoid the formation on their surfaces of deposits of chlorides 

 and albuminates of silver. 



These impregnations only succeed with fresh tissues. 

 352. Silver Nitrate : the Solutions to be employed (RANVIER). 

 The solutions generally employed by RANVIER vary in strength from 

 1 : 300 to 1 : 500. Thus 1 : 300 is used for the epiploon, pulmonary 

 endothelium, cartilage, tendon ; whilst a strength of 1 : 500 is 

 employed for the phrenic centre, and the epithelium of the intestine. 

 For the endothelium of blood-vessels (by injection) solutions of 

 1 : 500 to 1 : 800 are taken. 



M. DUVAL (Precis, p. 229) takes solutions of 1, 2, or at most 

 3 per cent. 



v. RECKLINGHAUSEN used, for the cornea, a strength of from 

 1 : 400 to 1 : 500 (Die Lymphgefasse, etc., Berlin, 1862, p. 5). 



ROBINSKI (Arch, de Physiol., 1869, p. 451) used solutions varying 

 between 0-1 and 0-2 per cent., which he allowed to act for thirty 

 seconds. 



ROUGET (Arch, de Physiol., 1873, p. 603) employed solutions as 

 weak as 1 : 750, or even 1 : 1000, exposing the tissues to their action 

 several times over, and washing them with water after each bath. 



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

 (Jen. Zeit. NaturL, xvi, pp. 313 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 I'Anat., 1876, 

 p. 200) took for the epithelia 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., 1876, p. 649) takes a solution of nitrate 

 of silver, 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 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 

 ( 356). For details see previous editions. 



REGAUD (Journ. Anat. et Phys., xxx, 1894, p. 719) recommends 

 for the study of lymphatics a, process devised by RENAUT, for the 

 details of which see also previous editions. 



