62 



ILLINOIS BIOLOGICAL MONOGRAPHS 



[182 



Per Cent. 

 100 



80 



40 



o 

 o 

 o 



o 

 b 



o 

 o 

 o 



o 

 o 

 o 



o 



o 

 o 



§ g; 



o 

 b 

 o 

 o 

 o 



Figure 28. Curve showing the effect of potassium cyanide on the oxygen absorption of 

 a marine sponge. Abscissa represents mols, per liter in sea water. Ordinate represents 

 the per cent of the rate of oxygen absoiption reduced by the potassium cyanide below the 

 normal during a unit time (150 minutes). Data taken from Hyman (1916). All data 

 taken from experiments on an individual sponge. 



sponge were taken) Fig. 28. The last two calculations are not made on the 

 same basis as the preceding curves but are sufficiently comparable to show that 

 both probably follow the same general law as the toxic activity of salts. A 

 curve formulated from data given in Experiment 1 , of Pittenger and Vander- 

 kleed's (1915) prelimJnary work on the goldfish as a test animal is shown in 

 Fig. 29. This is the same type of curve. This work of Pittenger and Vander- 



Figure 29. Digitalis. Velocity of fatality and survival time curves. Abscissa represents 

 per cent concentration. Data taken from Pittenger and Vanderkleed (1915). 



