158 The Mechanistic Conception of Life 



How can we explain the fact that fertiUzation saves the hfe 

 of the egg ? Let us make the following preliminary assumption : 

 The unfertilized egg contains a poison, or some faulty combina- 

 tion of conditions which, if oxidations take place, causes the 

 death of the egg. In the unfertilized but mature egg oxidations 

 take place. The spermatozoon carries into the egg among 

 other substances something which protects the egg against the 

 fatal effects of the oxidations, and allows them even to carry on 

 oxidations at an increased rate without suffering. We might 

 say that the mature but unfertilized egg is comparable to an 

 anaerobic being for which oxidations are fatal, and that the 

 spermatozoon transforms the egg into an aerobic organism. 



If we compare the eggs of different animals, we find great 

 differences in regard to the above-mentioned conditions. The 

 eggs of certain annelids (Polynoe) also perish rapidly if they, 

 become mature without being caused to develop, while the 

 eggs of the sea-urchin remain alive for a longer period of time 

 after they have become mature. The problem as to what 

 determines this difference has not yet been investigated. 



II 



The analysis of the process of fertilization by the spermato- 

 zoon shows that we must discriminate between two kinds of 

 effects, the hereditary effect and the activating or develop- 

 mental effect. The experiments on artificial parthenogenesis 

 make it very probable that the two groups of substances, the 

 substances which determine the heredity of paternal characters 

 and the substances which cause the egg to develop, are entirely 

 different. In this paper we are concerned only with the 

 second group of substances, namely, those which cause the 

 development of the egg. 



The analysis of the causation of development of the egg 

 by a spermatozoon has shown that the latter acts by carrying 

 at least two substances or groups of substances into the egg. 



