236 ELERV R. BECKER. 



Brilliant Cresyl Blue. Stains Opalina light blue in dilutions of 

 i to 50,000. In the reduction to the leuco-base, there is an 

 intermediate greenish hue. All the Opalina took the stain and 

 showed reduction of the dye. On readmittance of air, the blue 

 reappeared . 



A number of Nyctotherus stained blue with this dye, but showed 

 no reduction phenomena. 



Nile Blue. Stains Opalina blue-green in dilutions of i to 

 30,000. On reduction to the leuco-base the color disappears. 

 Readmittance of air causes green stains to reappear. 



Toluidine Blue. Stains Opalina violet. Reduced to leuco- 

 base. Color reappears on readmittance of air. Not all organ- 

 isms took the stain. 



Bismarck Brown. Does not stain Opalina. 



Methyl Green (Vital). Living Opalina do not stain, even in 

 dilutions of i to 1,000. In dilutions of i to 300 the dead ones 

 stained a beautiful violet, but showed no reduction of the dye. 



Vital Red. i to 2,000 does not stain Opalina. 



Isamine Blue. Does not stain Opalina in dilutions of I to 

 15,000 and i to 20,000. 



Trypan Blue. Does not stain Opalina in dilutions of i to 

 10,000 and i to 20,000. 



Trypan Red. Same results as Trypan blue. 



Carminate of Sodium. Same as Trypan blue. 



Fuchsin (Neutral). Same as Trypan blue. 



Rhodamine. In dilutions of i to 20,000 this dye will stain 

 Opalina a light pink. No reduction of this dye could be accom- 

 plished, although in a test tube the dye could be reduced to the 

 leuco-base by means of xinc and HC1. 



Neutral Red. Stains Opalina and certain granules and food 

 vacuoles in Paramecium pink, but no reduction could be accom- 

 plished in the hydrogen chamber. 



Methylene Blue. This dye stains Opalina blue almost at once. 

 It takes about ten minutes in order for it to stain Paramecium 

 well. A comparison of the rate of reduction of the dye by the 

 two ciliates would have been interesting, but the problem was 

 complicated by the fact that Opalina completely and uniformly 

 reduced the dve with which it is stained to the leuco-base within 



