526 METHODS FOR INVERTEBRATES. 



ROUSSEAU (Ann. Soc. Belg. Mic., xxiv, 1899, p. 51) stains in 

 nigrosin, picro-nigrosin, or indulin, or MAYER'S picro-magnesia 

 carmine. 



Prof. Dendy informs me that he uses Hickson's brazilin ( 378) a 

 great deal in his work on sponges. 



For intra vitam staining, see LOISEL, 207, ante, p. 130. 



For silvering, see 356. 



Sectioning. Calcereous sponges may be decalcified in alcohol, 

 acidified with hydrochloric or nitric acid, and then embedded in the 

 usual way. Siliceous sponges may be desilicified, 566. 



For ROUSSEAU'S methods, see 566. VOSMAER and PEKELHARING 

 decalcify with a solution of picric acid in absolute alcohol (see Zeit. 

 wiss. Mik., xv, 1899, p. 462). 



See also Johnstone-Lavis and Vosmaer, 179. 



Preparation of Hard Parts. Siliceous spicules are easily cleaned 

 by treating them on a slide with hot concentrated nitric or hydro- 

 chloric acid, or solution of potash or soda. The acids mentioned 

 are very efficient, but may attack the silex of some delicate spicules. 

 Potash solution is, therefore, frequently to be preferred, notwith- 

 standing that, in my experience, it does not give such clean pre- 

 parations. 



According to NOLL, eau de Javelle is preferable to any of these 

 reagents, see 544. 



Embryos and Larvae. MAAS (ZooL Jahrb., Abth. Morph., vii, 

 1894, p. 334) fixes larvse in liquid of Flemming or Hermann, one to 

 three minutes, and stains with borax-carmine, or with gentian violet 

 and Orange G (Flemming). He also (Zeit. wiss. ZooL, Ixvii, 1900, 

 p. 218) fixes young Sycons in absolute alcohol and stains with 

 ammonia carmine (spicules in situ). 



DELAGE (Arch. Zool. Exper., x, 1892, p. 421) fixes larvae of Spon- 

 gilla that have settled down on cover-glasses for three minutes in 

 absolute alcohol, stains in alcoholic carmine, and brings through 

 alcohol into oil of bergamot, then either mounts direct in balsam, or 

 detaches the larvse from the cover and imbeds in paraffin (three 

 minutes). 



GATENBY (Journ. Linnean Soc., 1920) uses methods for mito- 

 chondria, especially Champy-Kull and Kopsch. 



Protozoa.* 



994. Introduction. In the special study of the protozoa the 

 various reagents and methods of general cytology are in great part 



* By Dr. A. Drew, Imperial Cancer Research Fund. 



