105 



way the other end contains four nuclei; that no antipodal 

 cells are formed is a question of little importance. 



Subsequently the ovum and synergidae die and obliterate so 

 that of the four nuclei belonging to the sexual part of the 

 embryosac it is only the polar nucleus which remains alive. 

 That it is the polar nucleus which survives and not one of the 

 synergidal nuclei or even the oval nucleus has been proved by 

 Tredb beyond the possibility of doubt. The three antipodal 

 nuclei together with the chalazal polar nucleus abort also — 

 so that finally the only living nucleus inside of the embryosac is 

 the micropylar polar nucleus. 



This micropylar polar nucleus now divides into two cells, a 

 superior and an inferior endospermic cell; the inferior one 

 dies, the superior continues to divide and finally forms the 

 whole endosperm which is afterwards found inside of the 

 embryosac. 



This endosperm Treub considers to be a prothallium which 

 apogametically forms later on an embryo. 



As I do'nt think that anything can be said against Treub's 

 statements I think I may be allowed to draw the logical con- 

 clusion that the micropylar polar nucleus has the nature of a vege- 

 tative prothallial nucleus. 



The fusion of these two prothallial nuclei is therefore a 

 fusion of vegetative nuclei, a fact which frequently occurs. 



The vegetative nature of the polar nuclei has all ready been 

 pointed out by Karsten in his work on Gnetum , but Treub's 

 research brings the first basis for this assertion. 



Karsten on the same place assumes that the antipodal cells 

 are a reduced eggapparatus which he makes plausible by 

 Treub's discovery of the chalazogamy, reasoning that before a 

 sharp separation between porogamy and chalazogamy had deve- 

 lopped it would have been important for the plant to have had 

 an eggapparatus at both sides of the embryosac. This view 

 of Karsten, is as he points out strengthened by the fact that 

 this rudimentary eggapparatus afterwards becomes destroyed. 

 Treub's investigation of Balanophora showing the rudimentary 



