METHODS FOR INVEBTEBEATES. 477 



the organisms. They should be very weak, that is of 

 strengths varying between 1 : 10,000 and 1 : 100,000. For 

 cyanin, 1 : 500,000 is strong enough. 



As to the staining of the Nucleus, see Pezesmycei, Biol. 

 Centralh., vii, 1897, p. 321 j and as to that of the Granula, 

 the same aiithor, Zeif. iviss. Mik., xiii, 1896, p. 478. Also 

 LoisEL, § 208, 



Examination in a coloured medium in which the organisms 

 do not stain, but show up on a coloured background is some- 

 times helpful. Ceetes [Bull. Sue. Zool. de France, xiii, 1888, 

 p. 230) recommends solution of aniliu black — Infusoria will 

 live in it for weeks ; Fabee-Domeegue [Ann. de Microgr., ii, 

 1889, p. 545) concentrated solution of diphenylamin blue. 



919. Demonstration of Cilia (Waddinqton, Journ. Roy. Mic. 

 Soc, 1883, p. 185).^ — A drop of solution of tannin, or a trace 

 of alcoholic solution of sulphurous acid, added to the water 

 containing the living organisms. 



920. Fixing and Preserving.— For killing by heat see § 13. 

 Pfjtznee {Morfh. Jahrh., xi, 1885, p. 454) used concen- 

 trated solution of picric acid rim in under the cover. 



Bntz {Zool. Aiiz., iv, 1881, p. 575) adds liquid of 

 Kleinenberg to the water containing the organisms in a 

 watch glass. 



KouscHELT {ibid., v, 1882, p. 217) employs in the same 

 way 1 per cent, osmic acid, oi-, for Amoebae, 2 per cent, 

 chromic acid. 



Lansbeeg {ibid., p. 336) advises the same reagents, but 

 recommends bringing the organisms into the firing liqioid with 

 a pipette. 



For fixation with iodine (Kent) or iodine vapour (Oveeton), 

 see § 83. 



For sulphurous acid, § 62. 



Cattaneo {Bullettino Scientifico, iii and iv ; Journ. Roy. 

 Mic. Soc, 1885, p. 538) fixes for a few minutes with ^ per 

 cent, solution of chloride of palladium. 



Beass {Zeit. wiss. Mih., 1884, p. 39) employs a mixtui'e of 

 1 part each of chromic acid, platinum chloride, and acetic 

 acid with 400 to 1000 parts of water. 



Cektes {Comptes rend., Ixxxviii, 1879, p. 433) fixes with 



