CHA PTER XXX VI. 505 



The living specimens may be placed direct on the medium on the 

 slide, or may be killed by a short immersion in 10 per cent, acetic acid, 

 or boiling water. If the specimens are in alcohol they should be washed 

 in 10 per cent, acetic acid before mounting. After the cover glass is 

 put on, gently warm the slide, then allow to cool, and leave for one or 

 two weeks to dry and set. Ring the slide with a waterproof substance 

 and finally ring with a layer of Canada balsam. 



Personally, I often kill in 90 per cent, or absolute alcohol, leave for 

 a few days, and mount in Euparal (see 449). 



943. Crustacea. Some forms are very satisfactorily fixed with 

 sublimate. Such are the Copepoda and the larvae of Decapoda. 

 It is sometimes indicated to use the sublimate in alcoholic solution. 

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

 by means of weak osmic acid, and so are the Ostracoda. In many 

 cases the osmic acid will produce a sufficient differentiation of the 

 tissues, so that further staining may be dispensed with ; so for 

 Copilia and Phyllosoma. The pyrogallic process ( 374) may be 

 useful. GIESBRECHT takes for marine Copepods a concentrated 

 solution of picric acid in sea water, to which a little osmic and acetic 

 acid may be added. For fresh-water forms, ZACHARIAS (Zool. Anz., 

 xxii, 1899, p. 72) takes chromo-acetic acid. 



GriESBRECHT fixes larvae of Stomatopoda for five to ten minutes 

 in formol of 10 per cent, warmed to 40 or 50 C., opens them in sea 

 water and puts for one and a half to two and a half hours into formol 

 1 part and sea water 5 parts, and brings into alcohol of 70 per cent. 



STAFFERS (La Cellule, xxv, 1909, p. 356) fixes Sympoda in GILSON'S 

 copper formol, 115, or in HORNELL'S mixture of 100 parts of 5 per 

 cent, formol with 40 of alcohol ; and for softening the chitin puts 

 for twelve to thirty-six hours into 3 per cent, solution of sublimate 

 with 5 per cent, of nitric acid. 



NETTOVITCH (Arb. z. Inst. Wien, xiii, 1900, p. 3) fixes Argulus 

 with liquid of Telly esniczky, 52, warmed to 50 C. 



For FISCHEL'S intra-vitam stain of Cladocera with alizarin, etc., 

 see 207. 



944. Tracheata. KENYON (Tufttj^olL Stud., No. 4, 1896, p. 80) 

 fixes Pauropoda in Carnoy's acetic alcohol and chloroform, 85, 

 cuts them in tw T o for staining, etc., and embeds in celloidin followed 

 by paraffin. 



HENNINGS (Zeit. wiss. Mik., xvii, 1900, p. 311) takes Nitric 

 acid 16 parts, chromic acid of 0-5 per cent. 16 parts, sublimate 

 saturated in 60 per cent, alcohol 24 parts, picric acid saturated in 

 water 12, and absolute alcohol 42, fixes for twelve to twenty-four 



