SOME METHODS FOR LOWER ANIMALS. 479 



histological detail of these forms was cold saturated sublimate 

 solution warmed to 35 40 C. 



859. Turbellaria. For Bhabdocoela, BRADN (Zeit. f. wiss. 

 J//A-., iii, 1886, p. 398) proceeds as follows : For preparing 

 entire animals, the specimens are got on to a slide, lightly 

 flattened out with a cover, and killed by running under the 

 cover a mixture of three parts of liquid of Lang with one of 

 1 per cent, osmic acid solution. Other fixing media than 

 that described were not satisfactory. (BoHMio [ibid.'], com- 

 menting on this, says that for some of the tissues, such as 

 muscle and body parenchyma, nitric acid and picro-sulphuric 

 acid are very useful.) Sections may be made by the paraffin 

 method. 



DELAGE (Arch, de Zool. exp. et gen., iv, 2, 1886 ; Zeit. f. wiss. Mik., iii, 

 2, 1886, p. 239 ; Journ. Roy. Mic. Soc., 1886, p. 1073) strongly recommends 

 fixation (of Rhabdocoela Acoela) by an osmium-carmine mixture, for which 

 see loc. cit., or by concentrated solution of sulphate of iron. Liquid of 

 Lang was not successful. 



For staining, he recommends either the osmium-carmine stain or impreg- 

 nation with gold (-| formic acid, two minutes ; 1 per cent, gold chloride, ten 

 minutes; 2 per cent, formic acid, two or three days in the dark. It is well 

 to allow an excessive reduction to take place, and then lighten the stain by 

 means of 1 per cent, solution of cyanide of potassium). 



BOHMIG (Zeit. f. wiss. Mik., iii, 1886, p. 239) says that he has obtained 

 very instructive images with Plagiostomidae fixed with sublimate and 

 stained with the osmium-carmine. 



GRAFF (Organisation d. Turbellaria Acoela, Leipzig, 1891 ; 

 Zeit. f. wits. Mik., ix, 1, 1892, p. 76) says that chromo- 

 aceto-osmic acid, followed by haematoxylin, is good for the 

 skin, but will not afford a satisfactory preservation of the 

 Rhabdites, which in Accela and Alloioccela seem to be 

 destroyed by swelling. The same method is also good for 

 the parenchyma of Amphichcerus cinereus, Convoluta para- 

 doxa, and C. sordida. Sublimate is good for Convoluta 

 Poscoffensis. For some forms it is important to avoid picro- 

 carmine, which destroys the central parenchyma. The 

 nervous system may be investigated by the methods of 

 DELAGE. 



For Dendrocosla sublimate solutions, sometimes hot, appear 

 indicated for fixing. CHICHKOFF (Arch, de BioL, xii, 1892, 

 p. 438 ; Journ. Roy. Mic. Soc., 1893, p. 262) recommends 



