540 METHODS FOE INVERTEBRATES. 



small organisms (small worms and Crustacea as well as Ciliata) by 

 means of a drop of thick aqueous solution of cherry-tree gum added 

 to the water containing them (gum arabic and the like, it is stated, 

 will not do). The objects remain fixed in their places, with cilia 

 actively moving, and all vital processes retaining their full activity. 



CERTES (Bull. Soc. Zool. France, xvi, 1891, p. 93) has found that 

 an intra vitam stain may be obtained by adding methyl blue or 

 " violet dahlia, No. 170. " to the gum solution. 



JENSEN (after STAHL ; see Biol. CentralbL, xii, 1892, p. 558) 

 makes a solution of 3 grins, of gelatin in 100 c.c. of ordinary water 

 by the aid of heat. This makes a jelly at the normal temperature. 

 It is slightly warmed, and a drop of it is mixed in a watch-glass with 

 a drop of water containing the organisms. 



See also VOLK, ante, 886 ; STATKEWITSCH, Arch. Protistenk., v, 

 1904, p. 17 ; LYON, Amer. Journ. Phys., xiv, 1905, p. 427 (neutralised 

 gum). 



1019. Staining intra vitam. See hereon BRANDT (Verh. physiol. 

 Ges. Berlin, 1878) ; CERTES (Bull. Soc. Zool, 25 janv., 1881) ; and 

 HENNEGUY (Soc. Philom., 12 fev., 1881). See also 208. 



BRANDT recommends a 1 : 3000 solution of Bismarck brown ; 

 also (Biol. Centralb., i, 1881, p. 202) " a dilute solution of heemato- 

 xylin." 



"CERTES (op. cit,, pp. 21, 226, 264, and Zool. Anz., iv, 1881, pp. 208, 

 287) found that living Infusoria stain in weak solutions of cyanin, 

 Bismarck brown, dahlia, violet 5 B, chrysoidin, nigrosin, methylen 

 blue, malachite green, iodine green, and other tar colours, and 

 hsematoxylin. The solutions should be made with the liquid that 

 constitutes the natural habitat of the organisms. They should be 

 very weak, that is, of strengths varying between 1 : 10,000 and 

 1 : 100, OCO. For cyanin, 1 : 500,000 is strong enough. 



As to the staining of the Nucleus, see PRZESMYCKI, Biol. Centralb., 

 vii, 1897, p. 321 ; and as to that of the Granula, the same author, 

 Zeit. wiss. 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 sometimes helpful. 

 CERTES (Bull. Soc. Zool. de France, xiii, 1888, p. 230) recommends 

 solution of anilin black Infusoria will live in it for weeks ; FABRE- 

 DOMERGUE (Ann. de Microgr., ii, 1889, p. 545) concentrated solution 

 of diphenylamin blue. 



For the mitochondria and other granules, see FAURE-FREMIET 

 (Arch. d'Anat. micr., xi, p. 457). Dahlia in salt solution, Pictet's 

 fluid. Janus green, or crystal violet being useful. 



