286 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 



fertilization becomes an act which saves or prolongs life. 1 

 A simpler way of prolonging the duration of life of the mature 

 but unfertilized egg of the starfish consists in adding a trace of 

 KCN to the sea-water (about 5 or 6 drops of 1/10 of 1 per cent 

 KCN to 50 c.c. of sea-water). 



A. P. Mathews has continued these experiments and like- 

 wise found that the life of the unfertilized ripe eggs can be pro- 

 longed by lack of oxygen. 2 



This proves that the death of the mature but unfertilized 

 egg is if not determined at least accelerated by oxidations. 



What is the explanation of these facts ? We know that the 

 unfertilized but mature egg of the starfish is the seat of compara- 

 tively rapid oxidations which are possibly or probably lacking 

 in the unripe egg. These oxidations lead directly or indirectly 

 to the death of the mature egg, while their prevention saves the 

 life of the egg, at least for some time. The unfertilized mature 

 egg may be compared to an anaerobe. The nature of the life- 

 saving action of the act of fertilization may then be expressed 

 by the statement that by the act of fertilization the egg is trans- 

 formed from an anaerobe into an aerobe. It is possible that 

 the oxidations do not kill the unfertilized egg directly, but 

 only through the medium of physical or morphological changes 

 which follow or accompany the oxidations. 



The idea that fertilization saves the life of the egg by render- 

 ing it immune against oxidations finds support not only in the 

 fact that the life of the unfertilized egg of the starfish is pro- 

 longed if we deprive it of oxygen or inhibit oxidations through 

 the addition of KCN, but also in the fact that the unfertilized 

 egg of the sea-urchin lives much longer in sea-water than does 

 the unfertilized mature egg of the starfish. This should lead 

 us to expect that the rate of oxidations in the unfertilized but 



1 Loeb, " Ueber Eireifung, natiirliclien Tod und Verlangerung des Lebens beim 

 unbefruchteten Seesternei (Asterias forbesii) und deren Bedeutung fur die Theorie 

 der Befruchtung," Pftuger's Archiv, XCIII, 59, 1902; Untersuchungen, p. 237. 



2 A. P. Mathews, Am. Jour. Physiol., XVIII, 89, 1907. 



