ASYMMF/rRIC . 1 A 1 /> ) N/N' 



109 



centration and the temperature characteristics of toxic 

 action were identical for tlie two isomers. There are cases 

 in which it seems that none of these relations hold. GaUvSe 

 and Smarag-dova (1938) reported this situation in the 

 action of malic acid on the brood of two species of vivi- 

 parous fish, Lehistes rrticidafus and Platypoecilus macii- 

 latiis. 



In these experiments they compared the natural laevo- 

 rotatory with the racemic malic acid (the significance of 

 the use of a racemate will be indicated below). It was 

 found that the natural laevorotatory malic acid is less 

 toxic than the racemic. The toxic action of weak 

 (0.05%) solutions of the laevorotatory and racemic malic 

 acids on Lehistes reUculatus at different temperatures 

 (16% 18% 21°, 26°, and 31°) is recorded in Figure 17. It 

 is quite apparent that the temperature characteristics of 



c 

 o 

 u 



0) 



(1) 

 E 





0) 



o 



en 



c 



o 



en 

 o 



0.00330 0.00340 O00350 



Reciprocal of absolute temperature 



Fig. 17. Effect of temperature on the killing time of the fish 

 Lehistes reticulatus by the optical isomei-s of malic acid. The lower 

 graph represents the killing rate plotted logarithmically. (From Gause 

 and Smaragdova, 1939.) 



