248 



BOTANICAL GAZETTE 



[APRIL 



silver on the equimolecular basis. The same relative toxicity is 

 maintained here as in those tables, although greater concentration of 

 both salts is required for total inhibition. 



Here the two salts are practically equitoxic, so that in some cases, 

 with increasing concentration of the enzyme^ salts, which are eqmtoxic 

 become unequal in toxicity, while others that are not equitoxic under 

 certain conditions become so under other conditions. Perhaps the 

 only conclusion that can be safely drawn from this group of tests is that 

 the concentration of the enzyme influences relative toxicity, and that 

 a relation which holds for one concentration of the enzyme may not 

 hold for another four or five times greater. 



RELATIVE TOXICITY OF EQUICATIONIC SOLUTIONS 



By calculation" it may be determined that copper and lead of 



w/2048 



results it is seen that those solutions are about equitoxic 



other hand, w/1971 of barium is equicationic with coppe 



TABLE XX: Ethyl butyrate 

 Barium y lead, copper, and potassium in contemporaneous test 



BARIUM 



On the 

 w/2048? 



m 



Water 

 2048.. 

 1024. . 



Control 



0.00 

 0.00 

 0.00 



Enzyme 



Increase 



0.20 

 0.20 

 0.20 



0.20 

 0.20 

 0.20 



POTASSIUM 



2048 

 1024 



0.20 



O. 20 



0.20 

 0.20 



LEAD 



2048 

 1024 



O. TO 

 O. 20 



0.30 

 0.30 



0.20 



o.io 



COPPER 



2048 

 1024 



Enzyme .0125 per cent. Incubation 4 hours at 35° C 



" All of the equicationic calculations were made for me by Dr. Wm. N. Berg 

 of the Laboratory of Biological Chemistry of Columbia University. 



