606 INVERTEBRATES 



sublimate, and also with alcohol containing a little platinum 

 chloride. 



Kaiser {Biblioth. Zool, H. vii, 1, Halfte, 1891, p. 3) found that 

 a saturated aqueous solution of cyanide of mercury, warmed to 

 45° to 50° C, and allowed to act from fifteen to sixty minutes, 

 and then washed out with 70 per cent, alcohol, was the best of all 

 fixing media. 



1206. Nematodes. The impermeable cuticle is a great obstacle 

 to preparation. According to Looss {Zool. Anz., 1885, p. 318) 

 this difficulty may be overcome in the manner described in 

 § 587. 



Wash in 1 per cent, saline (if necessary) and fix in boiling 

 70 per cent, alcohol ; store in fresh 70 per cent, for examination. 

 If this method is properly applied the worms will die extended 

 and straight. For examination transfer to 70 per cent, alcohol 

 made up with 5 per cent, glycerin. Place small bottle of this 

 fluid, with worms, on incubator at 60° C, and allow to evaporate 

 slowly for about twenty-four hours or even two days, which 

 finally leaves the worms in viscid, almost pure, glycerin. Examine 

 in pure glycerin, or glycerin jelly. For rapid examination after 

 killing in alcohol, transfer to absolute alcohol for thirty minutes, 

 and clear in " white " creosote. (Leiper, in Science of the Sea, 

 London. John Murray. 1912), 



For fixing, most recent authors recommend sublimate solutions ; 

 chromic solutions seem to have a tendency to make the worms 

 brittle. 



But, according to Zur Strassen {Zeit. wiss. Zool., liv, p. 655), 

 Bradynema rigidum ought to be fixed for at least twelve hours in 

 mixture of Flemming. 



Augstein {Arch. Naturg., Ix, 1894, p. 255) takes for Strotigylus 

 filaria Mayer's picro-nitric acid. 



Vejdovsky {Zeit. wiss. Zool., Ivii, 1894, p. 645) advises for 

 Gordius 05 per cent, chromic acid (twenty-four hours). 



Lo Bianco employs for marine forms concentrated sublimate or 

 picro-sulphuric acid. 



Looss {Zool. Anz., xxiv. 1901, p. 309) prefers hot (80° to 90° C.) 

 alcohol of 70 per cent. 



Glaue {Zeit. wiss. Zool., xcv, 1910, p. 554) kills Ascaris in a 

 hot mixture of 100 parts of saturated sublimate, 100 of alcohol, 

 and 1 of acetic acid. 



Staining is frequently difficult, and sometimes alcoholic carmine 

 § 271, is the only thing that will give fair results. 



For thin sections, S. Doubrow and J. Rousset {Bull, d'hist. 

 appl., 1929) fix in mecuric chloride saturated in 80 p^* cent, 

 alcohol, with 5 per cent, acetic acid for from four to twelve hours. 

 Transfer to iodised alcohol for a few days, upgrade to 100 per 

 cent, alcohol, then butyl alcohol for twenty-four hours. Place 



