STUDIES ON PARAMECIUM. 77 



any of the acid dyes used, although these might stain the contents 

 of the food vacuoles, or the cytoplasm of dead or dying Para- 

 mecium. 



3. Animals with stained cytoplasm could live indefinitely in a 

 dilute solution of bismarck brown; in all of the other dyes used, 

 the stained paramecia eventually died unless they were removed 

 from the stain. The presence of the dye in the food vacuoles 

 but not in the cytoplasm was not necessarily fatal to Paramecium- 



4. Although the macronucleus could be stained while the 

 animal was still alive, such animals eventually died even though 

 removed from the stain. 



5. The stain disappeared from the cytoplasm of the living 

 animals within a few hours after their removal from the dye 

 solution. 



6. The exposure to light of Paramecium having the cytoplasm 

 stained by certain dyes, or of Paramecium in a concentrated 

 solution of eosin, produced a marked avoiding reaction within 

 five seconds. The animals giving this reaction died much more 

 rapidly in strong light than in darkness. 



BIBLIOGRAPHY. 

 Baldwin, W. M. 



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 Ball, G. H. 



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'26 Vital Staining and Reduction of Vital Stains by Protozoa. BIOL. BULL.. 



50, 235-238. 

 Causey, D. 



'26 Mitochondria in Ciliates with Especial Reference to Paramecium candatum 



Ehr. Univ. Calif. Publ. Zool., 28, 231-250, pis. 22-24. 

 Child, C. M., and Deviney, E. 



'26 Contributions to the Physiology of Paramecium caudatnm. Jour. Exp. 



Zool., 43, 257-312. 

 Crozier, W. J. 



'23 A Note on the Reaction of Protoplasm. Proc. Soc. Exp. Biol. and Mcd., 



21, 58- 

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'26 A Mutation in Paramecium aurelia. Jour. Exp. Zool., 4-4, I33i57. i !>' 

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'26 Staining Protozoa with Janus Green B. Stain Technology, /, 35~36. 

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