CHAPTER XXXVI. 521 



to a slide with euparal, dehydrates by adding alcohol by drops, and 

 adds euparal and a cover. See also WOODLAND, Quart. Journ. Micr. 

 Sci., xlix, 1905, p. 307. 



Ccelenterata. 



976. Thread-Cells. IWANZOFF (Bull. Soc. Nat. Moscou, x, 1896, 

 p. 97) advises for the Nematocysts of Actiniae maceration by HERT- 

 WIGS' method, 534, or better, fixation for two to five minutes with 

 vapour of osmium followed by a short washing with sea water or distilled 

 water. 



. For Medusae he also advises HERTWIGS' method, 526, or treat- 

 ment with a solution containing methyl green and gentian violet with a 

 little osmic acid. 



977. LITTLE (Journ. App. Mi-c., vi, 1903, p. 2116 ; Journ. Roy. 

 Mic. Soc., 1903, p. 237) kills Hydra in hot saturated sublimate in 

 70 per cent, alcohol, washes with alcohol, stains for" five minutes in 

 strong solution of methylen blue, dehydrates rapidly, clears with 

 cedar or bergamot oil, and mounts in balsam. Nematocysts blue, 

 the rest unstained. 



978. Actinida. Anaesthetise in menthol ( 15), which will take 

 some twelve hours or more. For ordinary sea anemones, formalin 

 (5 to 10 per cent.) followed by formalin spirit is to be preferred. 

 For corals, such as Caryophyllia, Alcyonium or Grorgonia, anaesthe- 

 tise, and then add hot corrosive sublimate or 5 per cent, formalin, 

 followed by cold saturated corrosive sublimate. Ninety per cent, 

 spirit, not allowed to get weaker than 70 per cent., gives good results 

 for anatomical work (ALLEN and BROWNE, loc. cit.). 



For other narcotisation methods see 15 to 26. 



979. Fixation. In Le Attinie, Fauna u. Flora d. Golfes v. Neapel, 

 ANDRES says that hot corrosive sublimate often gives good results. 

 In the case of the larger forms the solution should be injected into 

 the gastric cavity. 



Freezing sometimes gives good results. A vessel containing 

 Actiniae is put into a recipient containing an ice and salt freezing 

 mixture and surrounded by cotton- wool. After freezing, the block 

 of ice containing the animals is thawed in alcohol or some other 

 fixing liquid. 



DUERDEN (Journ. Inst. Jamaica, ii, 1898, p. 449) narcotises with 

 magnesium sulphate, 24, and fixes with formol of 3 to 5 per cent. 



980. Maceration. For the HERTWIGS' method (Jen. Zeit., 1879, 

 p. 457) see 526. The tissues should be left to macerate in the 

 acetic acid for at least a day, and may then be teased in glycerin. 



