466 CHAPTER XXXIV. 



Some forms are very satisfactorily fixed with sublimate. 

 Such are the Copepoda and the larvas of Decapoda. It is 

 sometimes indicated to use the sublima,te in alcoholic solution. 

 Some Copepoda, however (Copilia, Sapphirina), are better 

 preserved by means of weak osmic acid, and so are the Ostra- 

 coda. In many cases the osmic acid will produce a sufficient 

 differentiation of the tissues, so that further staining may 

 be dispensed with ; Copilia and Phyllosoma are examples of 

 forms that may be prepared in this simple manner. The 

 pyrogallic process ( 361) may often prove helpful in the 

 study of such forms. 



For Ostracoda, MULLER (Fauna u. Flora d. Golfes von Neapel, 

 xxi [Ostracoda], 1894, p. 8) recommends fixing- in a mixture 

 of five parts of ether and one of absolute alcohol, followed 

 by 70 per cent, alcohol. 



GIESBRECHT takes for marine Copepods a concentrated 

 solution of picric acid in sea water. 



KENYON (Tufts. Coll. Stud., No. 4, 1896, p. 80j fixes 

 Pauropoda in Carnoy's acetic alcohol and chloroform, 83, 

 cuts them in two for staining, etc., and imbeds in celloidm 

 followed by naraffin. 



DCBOSCQ (Arch. Zool. Expi'r., vi, 1899, p. 481 ; Journ. Soy. 

 Hie. Soc., 1899, p. 544) fixes Chilopoda in a mixture of 

 equal parts of 1 per cent, chromic acid, 10 per cent, nitric 

 acid, and 95 per cent, alcohol, or in a mixture of one part 

 of glacial acetic acid and ten of absolute alcohol. 



See also 101. 



836. Test for Chitin (ZANDER, P-fluger's Arch.f. d. ges. Plnjs., 

 Ixvi, 1897, p. 545 ; Zeit. f. wt#*. Nil;., xv, 2, 1898, p. 214).- 

 The object is placed in water under a cover-glass, arid treated 

 for a short time with a drop of freshly prepared solution of 

 iodine in iodide of potassium. This is then partly removed 

 with water, and a drop of concentrated chloride of zinc 

 added. This is in its turn removed with water as far as 

 possible, and the violet reaction is obtained. Weaker 

 solutions of zinc chloride may be taken, but the reaction is 

 not so sharp. 



837. Methods for Clearing and Softening Chitin. The employ- 

 ment of eau de Javelle or can Je Labarraque, as suggested 



