484 CHAPTER XXXTV. 



Asterina in osmic acid, brings into liquid of Miiller for twelve to fourteen 

 hours, imbeds in celloidin followed by paraffin (see 166), and stains 

 sections with carmalum or Delafield's hsematoxylin, best after a foregoing 

 stain of twenty-four hours in borax carmine. 



Coelenterata. 



866. Thread-cells. IWANZOFF (Bull. Soc. Nat. Moscou, x, 1896, 

 p. 97) advises for the Nematocysts of Actinia maceration by the HERTWIGS* 

 method, 538, 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 the HEETWIGS' method, 538, or treatment 

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

 osmic acid. 



867. Actinida. Narcotisation. For suitable narcotisation 

 methods see 13 to 23. 



Fixation. In Le At tints, 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, and a further 

 quantity of the liquid be poured over the animals. 



Freezing sometimes gives good results. A vessel contain- 

 ing 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. 



See also Lo BIANCO, loc. cit., p. 448. 



Maceration. For the HEKTWIGS' method (Jen. Zeit., 1879, 

 p. 457) see 538. The tissues should be left to macerate in 

 the acetic acid for at least a day, and may then be teased 

 in glycerin. 



LIST (Zeit. f. wiss. Mik., iv, 2, 1887, p. 211) treats tentacles 

 of Anthea cereus and Sagartia parasitica for ten minutes with 

 a mixture of 100 c.c. of sea water with 30 c.c. of Flemming's 

 strong liquid ( 47), then washes out for two or three hours 

 in 0*2 per cent, acetic acid, and teases in dilute glycerin. 

 Picro-carmine may be used for staining. 



868. Zoantharia with Calcareous Skeletons are difficult to 

 deal with on account of the great contractility of the polyps. 

 Sublimate solution, which ought very often to be taken 

 boiling, sometimes gives good results. DE CASTELLAKNAU 

 (La Est. Zool., de Napoles, p. 132) says that this process 



