Chapter I 

 FERTILIZATION 



/. Historical Introduction 



The first author who described the nucleus as the organ 

 of heredity was Ernst Haeckel. In the second volume of 

 his ''Generelle Morphologic dcr Organisuicn/'^ he estab- 

 lished this conception, founding it especially on the be- 

 havior of the nucleus during cell-division. For him the 

 "inner nucleus has the work of transmitting the hered- 

 itary characters, the outer plasm has the part of adapta- 

 tion, accommodation or adjustment to the conditions of 

 the outer w^orld." And just as the nucleus plays its princi- 

 pal role in propagation, so is nutrition the chief task of 

 the plasma. In the lowest, non-nucleated organisms the 

 two functions are not yet separated. 



For almost ten years this prophetic utterance re- 

 mained without noticeable effect on the progress of cell- 

 anatomy and the theory of fertilization. It was only 

 when Oscar Hertwig discovered that in fertilization the 

 spermatozoids copulate with the nucleus of the egg-cells 

 that Haeckel's idea became the starting-point for a new 

 line of investigation.^ Hertwig first observed this fact 

 in the eggs of the Echinidae. 



R. Hertwig, Fol, Selenka, Flemming, and others, have 

 lent their support to this opinion by further investigations, 



ipp. 287-289. 1886. 



^Hertwig, O. Beitrage ziir Kenntnis der Bildung, Befruchtung 

 und Theilung des thierischen Eies, Morphol. Jahrb. 1: 347. 1875. 



