54 



BIOLOGY OF DEATH 



TABLE 4 



Experiments of Loeb and Lewis on the Prolongation of Life of the Sea-urchin 



Egg by KCN 



Concentration of 

 KCN 



Pure sea-water 



n/64000 KCN 



n/16000 KCN 



n/8000 KCN 



n/4000 KCN 



n/2000 KCN 



n/1000 KCN 



n/750 KCN 



n/400 

 n/300 

 n/250 

 n/200 

 n/100 



KCN 

 KCN 

 KCN 

 KCN 

 KCN 



Result of fertilization after a 75 hours' stay 

 in the solution 



No egg segments 



No egg segments 



No egg segments 



Very few eggs show a beginning of seg- 

 mentation 



Very few eggs show a beginning of seg- 

 mentation 



Few eggs go through the early stages of 

 segmentation 



Many eggs segment and develop into swim- 

 ming larvae 



Many eggs segment and develop into swim- 

 ming larvae 



A few eggs develop into swimming larvae 



No egg segments 



No egg segments 



No egg segments 



No egg segments 



From this table it is seen that in concentrations of 

 KCN from n/750 to n/1000 the eggs developed perfectly 

 into swimming larvae. In other words, by the addition 

 of this very small amount of KCN, the life period has 

 been prolonged to three times what it would normally 

 be under the same environmental conditions. Concen- 

 trations of KCN weaker than n/1000 were incapable of 

 producing this result, or at best, if development started, 

 the process came very quickly to an end. In stronger 

 concentrations than n/400 the eggs were evidently poi- 

 soned, and no development occurred. 



Other experiments of Loeb's show that the lethal 

 effects of various toxic agents upon the egg cell may be 

 inhibited or postponed for a relatively long time, by 



