EFFECTS ON PROTOZOA 



751 



Table 6-15 

 Arsenical Concentrations Lethal to Ciliates" 



Arsenical 



Paramecium caudatum^ 

 Di9?-AsOAs-di9? 

 Di^J-AsCl 

 99-AsO 



Et-chlorovinyl-AsCl 

 p-Cl-97-AsCl 

 DiMe-AsOAs-diMe 

 gp-AsClg 

 DiMe-AsCl 

 Et-AsO 

 Et-AsBrg 

 Me-AsCla 

 Et-AsCL 



0.02 

 0.07 

 0.36 

 0.45 

 0.47 

 0.85 

 0.89 

 1.4 

 4.6 

 7.0 

 7.9 

 14.3 



1800 

 514 

 100 



77 



42 



41 



26 

 7.8 

 5.1 

 4.6 

 2.5 



Colpidium colpoda' 

 Di9?-AsBr 

 Di9?-AsOAs-di99 

 Di^j-AsCl 

 97-AsO 

 2).Cl-(p-AsCl2 

 DiMe-AsCl 

 Diq9-As-sulfide 

 Me-AsCl^ 

 DiMe-AsOAs-diMe 



0.0044 



0.0045 



0.0056 



0.109 



0.303 



0.443 



0.475 



0.500 



0.645 



2480 



2420 



1950 



100 



36 



25 



23 



22 



17 



" The terminologies are a little irregular and I am not certain that all the com- 

 pounds have been correctly designated; e.g., I do not know what diphenylarsenious 

 oxide is — perhaps it is di(j9-AsOAs-di<j9, which splits readily in aqueous medium. 



^ The concentration required to kill the organisms in 3 min. 



" Relative activity based on 100 for phenylarsenoxide; for C. colpoda the value 

 for this compound is maximal. 



'^ From McCleland and Peters (1919). 



« From Walker (1928). 



