MACERATION CORROSION 249 



Anot. Abtfi., 1897, p. i:J6 (1 to = per cent, solution of MalTs or INIerck's 

 panereatin, with 0-8 per cent, of carbonate of soda ; for demonstrating 

 adenoid tissue in iiaraflin sections). 



CORROSION 



584. Corrosion is the operation of destroying the soft parts 

 that surround hard parts that it is desired to study — in short, 

 a means of cleansing hard parts for microscopic study. It has 

 been appHed to the removal of surrounding tissue from injected 

 vessels or cavities. For this, see Altmann's Method {Arch. mik. 

 Anat., 1879, p. 471, or previous editions) ; also Rejsek {Bibliogr. 

 Anat., iv, 1897, p. 229) ; Bruiil {Anat. Anz., xiv, 1898, p. 418) ; 

 Denker {Anat. Hefte., 1900, p. 300) ; Thoma and Fromherz 

 {Arch. Entzvickelungsmech, vii, 1898, p. 678) ; Peabody {Zoo. Bull. 

 Boston, 1897, p. 164). The following sections relate chiefly to 

 the cleansing of native hard parts. 



585. Caustic Potash, Caustic Soda, Nitric Acid. Boiling, or 

 long soaking in a strong solution of either of these is an efficient 

 means of removing soft parts from skeletal structures (appendages 

 of Arthropods, spicules of sponges, etc.). 



586. Eau de Javelle (Hypochlorite of Potash) (Noll, Zool. 

 Anzeig., cxxii, 1882, p. 528). A piece of sponge, or similar object, 

 is brought on to a slide and treated with a few drops of eau de 

 Javelle, in which it remains until all soft parts are dissolved. 

 (With thin pieces this happens in twenty to thirty minutes.) 

 The i^reparation is then cautiously treated with acetic acid, which 

 removes all precipitates that may have formed, dehydrated, and 

 mounted in balsam. 



The process is applicable to calcareous structures. 



587. Eau de Labarraque (Hypochlorite of Soda) may be used in 

 the same way as eau de Javelle. Looss {Zool. Anzeig, 1885, p. 333) 

 finds that either of these solutions will completely dissolve chitin 

 in a short time with the aid of heat. For this purpose the com- 

 mercial solution should be taken concentrated and boiling. 



If solutions diluted with 4 to 6 volumes of water be taken, 

 and chitinous structures be macerated in them for twenty-four 

 hours or more, according to size, the chitin is not dissolved, but 

 becomes transparent, soft and permeable to staining fluids, 

 aqueous as well as alcoholic. The most delicate structures, 

 such as nerve-endings, are stated not to be injured by the treat- 

 ment. The method is applicable to Nematodes and their ova, 

 and also to the removal of the albumen from ova of Amphibia, 

 etc. 



588. Diaphanol. See § 1184. This is an important new fluid. 



