278 OHAPTEE XXIII. 



p. 678) ; Peabody {Z. Bull, Boston, 1897, p. 164). The fol- 

 lowing sections relate chiefly to the cleansing of native hard 

 parts. 



551. 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, spicula of sponges, etc.). 



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

 Anzeig., 122, 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 preparation 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. 



653. Eau de Labarraque (Hypochlorite of Soda) maybe used 

 in the same way as eau de Javelle. Looss {Zool. Anzeiij., 

 1885, p. 333) finds that either of these solutions will com- 

 pletely dissolve chitin in a short time with the aid of heat. 

 For this purpose the commercial 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 dis- 

 solved, 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 treatment. The method is applicable to 

 Nematodes and their ova, and also to the removal of the 

 albumen from ova of Amphibia, etc. 



