REUBEN BLUMENTHAL. 



rate of increase in volume of eggs exposed to the same concentra- 

 tions of HCN but for varying lengths of time. Volume here is 

 also plotted against time in hypotonic sea-water. KCN, on the 

 other hand, caused a decrease in the volume of the eggs, when 

 placed in hypotonic sea-water, below that of the control exposed 

 to sea-water. The volume of the eggs varied inversely as the 

 concentrations of KCN. Fig. 3 shows the rate at which the 

 volumes of the eggs decrease with increase in concentration of 

 KCN. 



3WO 

 1300 

 3200 



3/00 



Z6oo 



2700 

 Uoo 

 2500 

 }<fOO 



1300 



1100 



voo 



2000 



nou 



/SCO 



nco 



Hn/nurc EXPOSURES TO xcn 



2 3 <" ? 6 7 d 9 K> 



MIHUTCtS IH HYfOrO/i/C SCA-UATfR- 



FIG. 3. Volumes of eggs after exposure to KCN showing the rate of decrease 

 in volumes with increase in concentration of KCN. Control was exposed to 100 

 per cent, sea-water. 



The pH of the HCN solutions varied only slightly, being 7.2 

 to 7.4, while the pH of the KCN solutions remained at 7.4. The 

 work of Lucke and McCutcheon ('260) shows that the volume of 

 Arbacia eggs is independent of the pH of the solution except in 

 cases where the pH is so high or so low as to injure or kill the 

 eggs. According to the same authors ('266) temperature does 

 have an effect on the volume of the eggs in hypotonic sea-water. 

 Although no attempt was made to keep the temperature constant 

 during the experiments, an accurate record, taken every half hour 

 during the experiments, was kept of the temperature of the 

 laboratory. Conditions at Woods Hole are such that the temper- 

 ature rarely varied 2 from 22 C. 



Eggs which had been exposed to N/^oo HCN and N/^oo KCN 

 for 60 minutes, by which time they had reached their maximum 



