242 



BOTANICAL GAZETTE 



[APRIL 



'/ 



directly with the concentration of the reagent. 



The amount of the precipitate varies 



TABLE X: Copper and lead in contemporaneous test 



COPPER 



m 



Water 



16384. 

 8ig2, 



4096, 



2048 



1024 



Reagent 



Control 



0.00 

 0.05 



o. 10 

 o. 20 



c 40 



o. 10 

 o. 10 



o 

 o 

 o 



IS 



18 



23 



0.40 



Enzvn' e 



Increase 



0.20 

 0.20 

 0.20 

 O- 22 

 0.26 

 0.40 



o. 10 



O. 10 



0.05 



0.04 



0.03 



0.00 



LEAD 



o. 10 

 o. 10 



0-15 



o. 20 

 0-35 



0.20 

 0.20 

 0.25 

 0.25 

 0.40 



o. 10 

 o.io 



o.io 



0.05 

 0.05 



Enzyme 0.05 per cent. Incubation 5 hours at 40 C. 



All the vials except the w/16384 contained sediment at the close 

 of incubation. The figures for copper are practically a duplicate of 

 those in Table IX. Lead seems to be not quite so toxic as copper in 



TABLE XI: Copper, lead^ and zinc in contemporaneous test 



COPPER 



nt 



4096 



2048 

 1024 



Reagent 



O 



o 



o 

 o 



10 

 20 



40 



70 



Control 



o. 17 

 0.23 

 0.40 



0.70 



Enzyme 



0.22 

 0.26 

 0.40 

 0.70 



Increase 



0.05 

 0.03 

 0.00 

 0.00 



LEAD 



4096 

 2048 

 1024 



ZINC 



4096 

 2048 

 1024 



O.IO 



0.20 



0.40 



0.85 



Enzyme 0.05 per cent. Incubation 5 hours at 40"" C. 



