OTHEK METHODS FOR PROTOZOA. 381 



drop of water that contains them. But generally speaking 

 it is best to employ only the vapour of the solution, exposing 

 the organisms to its action for not more than from ten to 

 thirty minutes) . 



The objects having been covered, the excess of liquid is 

 removed by means of blotting paper, and the following stain 

 is allowed to flow in : 



Glycerin . . . . . .1 part. 



Water 1 



Picro-carmine . . . . . 1 

 (Eosin may also be used. Soluble anilin-blue does not give 

 such good results.) The stain should be placed at the edge 

 of the cover and the slide put away in a moist chamber in 

 order that the water may evaporate very slowly and be 

 changed very gradually for the glycerin-mixture ; if this pre- 

 caution is not taken, shrinkage may occur. When the 

 exchange has taken place, strong glycerin may be added and 

 gradually substituted for the dilute glycerin. 



Certes states that the organisms thus prepared are fixed 

 perfectly in their natural form, and allow of the study of the 

 minutest detail of cilia, flagella, and the like, with the highest 

 powers ; the green colouration of Euglenae and Paramecia is 

 preserved. The nuclear structures are sharply brought out 

 by the picro-carmine. 



758. SA.VILLE KENT and BERTHOLD (Manual of the Infusoria ; 

 Journ. Roy. Hie. Soc., 1883, p. 451) prefer a brownish-yellow 

 solution of potassium iodide to osmic acid for fixing. 



759. Demonstration of Cilia (WADDINGTON, Journ. Roy. Mic. 

 Soc., 1883, p. 185). Solution of tannin, or a trace of alco- 

 holic solution of sulphurous acid. 



760. Other Methods for Protozoa. 



MAUPAS, Comptes rend., 1879, P sem., p. 1276, and 2"' e sern., p. 251. 

 (Fixation with alcohol followed by picro-carmine, glacial acetic acid, and 

 glycerin). 



J)u PLESSIS, VOGT et YUNG, Trait. Anat. Comp. Prat., p. 92. (Fixation 

 with O2 per cent, solution of corrosive sublimate. Let the preparation dry 

 up, and if the organisms have preserved their shape, stain, and mount in 

 balsam). 



GEZA ENTZ, Zool. Anz., 1881, p. 575. (Fixation of the organisms in a 

 watch-glass with liquid of Kleinenberg. Wash out with alcohol, stain for 



