160 The Mechanistic Conception of Life 



this rapid death of the sea-urchin egg, after artificial membrane 

 formation, can be prevented either by withdrawing the oxygen 

 from the egg or by inhibiting the oxidations in the egg by the 

 addition of a trace of potassium cyanide. The membrane 

 formation, therefore, causes the rapid death of the egg through 

 an acceleration of oxidations. Warburg has recently shown 

 that the artificial membrane formation in the unfertilized sea- 

 urchin egg causes the same increase in the rapidity of oxidations 

 as the entrance of a spermatozoon. 



If we wish to cause the unfertilized eggs to develop to the 

 pluteus stage after the membrane formation, we have to subject 

 them to a second treatment. This may consist in putting them 

 about fifteen minutes after the membrane formation into a 

 hypertonic solution of a certain osmotic pressure (for instance, 

 50 c.c. of sea-water+8 c.c. n/2j NaCl) for one-half to one hour. 

 If, after this time, they are put back into normal sea-water they 

 no longer perish, but develop into normal larvae. I ventured 

 the hypothesis that the artificial membrane formation causes 

 a rapid increase of the oxidations in the egg and in this way 

 causes it to develop, but that these oxidations lead to the rapid 

 decay of the eggs at room temperature for the reason that the 

 egg contains a toxic substance, or a toxic complex of conditions, 

 which in the presence of oxidations leads to the rapid death of 

 the egg. The second treatment serves the purpose of rendering 

 the egg immune against the toxic effects of the oxidations. 



If we first cause the artificial membrane formation in the 

 unfertilized egg by any of the various means which I have 

 described in former papers, and if we afterward treat the eggs 

 for a short time with a hypertonic solution, they develop after 

 being transferred to normal sea-water in the same way as if a 

 spermatozoon had entered them. They reach the successive 

 larval stages, develop into a blastula, gastrula, and pluteus, and 

 live as long as the larvae produced from eggs fertilized by a 

 spermatozoon. 



