ARTIFICIAL PARTHENOGENESIS IN ANNELIDS 689 



results were actually due to the substances extracted from 

 the spermatozoon. But his experiments are certainly in the 

 right direction. 



The idea that the spermatozoon and the substances which 

 cause parthenogenesis act only catalytically, has a great 

 bearing upon the theory of life phenomena. It means that 

 if we accelerate the processes of cell-division in the mature 

 egg (by specific catalyzers) the egg can live; but if these 

 processes occur too slowly at the ordinary temperature (as is 

 the case in the unfertilized egg in normal sea-water), the 

 egg dies. The introduction of the catalytic substances which 

 accelerate the processes of development saves the life of the 

 egg. This may be made intelligible on the following 

 assumption. Two kinds of processes are going on in the 

 mature egg after it has left the ovary. The one leads to the 

 formation of substances which kill the egg ; the other leads 

 to the formation of substances which allow growth and cell- 

 division, and are not poisonous. We may use as an illustra- 

 tion Pasteur's well-known experiments on the behavior of 

 yeast cells in the presence and absence of atmospheric 

 oxygen. In the presence of oxygen the yeast cells multiply 

 on a sugar solution, while the zymase effect is comparatively 

 small. In the absence of oxygen the multiplication of cells 

 is limited or may stop, while the zymase effect becomes more 

 prominent. The products of alcoholic fermentation are 

 comparatively harmless for the yeast cell, and for this reason 

 an increase in the fermentative activity of the cell does not 

 cause the death of the yeast. I imagine that matters are 

 similar in the mature egg cell after it has left the ovary, 

 with this difference, perhaps, that the substances formed (by 

 fermentation?) in the egg cell are more poisonous for the 

 egg than the alcohol and the other products of fermentation 

 are for the yeast. The process that causes the death of the 

 egg cell and the one that causes cell-division are at least 



