STUDIES ON PARAMECIUM. 

 III. THE EFFECTS OF VITAL DYES ON Paramecium caudatum* 



GORDON H. BALL, 

 UNIVERSITY OF CALIFORNIA, SOUTHERN BRANCH. 



The Protozoa are in many respects more suited for a study 

 of the action of vital dyes on protoplasm than are Metazoan 

 tissues, since with unicellular animals it is possible to determine 

 readily a change in the normal life of the cell as well as the exact 

 moment of death or recovery. The protoplasm of Paramecium 

 may be used as a means of studying any selectivity towards the 

 entrance of various vital dyes, as well as the affinity of the dye 

 for different elements in the cell. On the other hand, caution 

 should be observed in applying results obtained in this group of 

 animals to any other group without adequate confirmatory 

 evidence. 



MATERIAL AND METHODS. 



The animals used belonged to a "conjugating" clone of 

 Paramecium caudatum (Race 385-1, Ball, 1925), which has been 

 maintained in culture for over four years. The dyes were 

 obtained from the various sources indicated in Tables I. and II. 

 Usually, the stock solutions were made up with distilled water, 

 in such concentrations that only a very small volume of dye 

 solution was added to a relatively large volume of culture fluid 

 containing the Paramecium. However, those dyes in which the 

 lethal concentration was only slightly less than the maximum 

 solubility were made up in the culture medium itself, since 

 ordinary distilled water is usually fatal to these animals. The 

 organisms were freed from the stain by centrifuging and washing 

 them in Paramecium-free hay infusion drawn from the stock 

 cultures. 



* These investigations were made possible by a grant from the Board of Research 

 of the LTniversity of California. 



