56 BIOLOGY OF DEATH 



painstaking and brilliant researches, extending over a 

 number of years, show that when we say that fertilization 

 is an essential condition for the continued life of the 

 germ-cells outside the body, our language tends to ob- 

 scure the most important fact, which is simply that for 

 the continuation of life in these cells only certain internal 

 physico-chemical conditions and adjustments' must be 

 realized. It makes no essential difference to the result 

 whether these conditions are realized through the 

 intervention of the sperm, as in normal fertiliza- 

 tion, or by purely artificial chemical methods initiated, 

 controlled and directed at every step by human agency. 

 We can, in other words, regard all cases of suc- 

 cessful artificial parthenogenesis as fundamentally a con- 

 tribution to the physiology of natural death, and a demon- 

 stration of its essentially mechanistic basis. The condi- 

 tions of continued existence are physical and chemical, 

 and controllable as such. The methods finally worked out 

 as optimum afford a complete demonstration of the thesis 

 we have just stated. Thus, for example, the unfertilized 

 egg of the sea-urchin, Strongylocentrotus purpuratus, 

 will continue in life and develop perfectly normally if it 

 is subjected to the following treatment: The eggs are 

 first placed in sea-water to which a definite amount of 

 weak solution of butyric acid has been added (50 cc. of 

 sea-water + 2.8 c.c. n/10 butyric acid). In this solution 

 at 15 C. the eggs are allowed to remain from l 1 /^ to 3 or 

 4 minutes. They are then transferred to normal sea- water, 

 in which they remain from 15 to 20 minutes. They are 

 then transferred for 30 to 60 minutes at 15 C. to sea-water 

 which has had its osmotic pressure raised by the addition 

 of some salts (50 c.c. of sea-water+8 c.c. of 2y 2 m NaCl, or 

 2y 2 m NaCl+KCL+CaCl 2 in the proportion in which these 



