170 Fertilization 



and in consequence of this it is quite generally recognized 

 at present in zoological science. 



In the field of botany Strasburger has the merit, by 

 investigations of many years' duration, of having defi- 

 nitely proved the theory that fertilization consists essen- 

 tially in the union of the nuclei. His first studies on the 

 fertilization of the conifers, and later on the same process 

 in the angiosperms^ now form the foundation of this part 

 of our knowledge. 



The other organs of the protoplasts take no part in 

 fertilization during copulation. And since, in spite of 

 this, the derivatives of the fertilized egg-cell possess later 

 the characteristics of both parents, it is clear that a trans- 

 mission to them of the hereditary characters from the 

 fertilized nucleus must take place. This transmission, 

 however, has, at least so far, eluded observation. But 

 many facts, even outside the scope of the theory of fer- 

 tilization, speak in favor of its existence. 



It is my intention to put together in this Section, as 

 completely as possible, all the facts that might throw any 

 light on the nature of this transmission. The prevailing 

 conception regards this process as a dynamic one, while 

 my hypothesis of intracellular pangenesis assumes a 

 transport of material particles as bearers of the hereditary 

 characters. Therefore it is a question of ascertaining 

 which of these two conceptions is best supported by the 

 material available for observation. 



^Strasburger, E. Ueher Befruchtung und Zelltheilung, 1878. 

 Neue Untersuchungen iiber den Befruchtungsvorgang bei den Phane- 

 rogamen, 1884. 



