15 



■ outer integument is formed, whereas the inner 

 one is just beginning to become visible. Mag. X 580. 



Fig. 8. Oenone Imthurni. Young ovule quite surrounded 

 by the outer integument. The stretching of the 

 inner integument and of the nucellus has not 

 yet taken place. The spore mothercell has dividud 

 into two cells of which the lower one is the 

 megaspore. Mag. x 58^- 



Fig. 4. Oenone Imthurni. Nucellus in almost the same 

 stage as the former figure. Megaspore entirely 

 formed. Mag. x 10^0. 



Fig. 5. Oenone Imthurni. A little older stage of the nu- 

 cellus. Both cells, which hâve developed from the 

 spore mother-cell are binucleated, in the megaspore 

 the lower one of the nuclei is aborting. Mag. X 1000. 



Fig. 6. Mourera fluviatiUs. Nucellus with inner integument 

 of a young ovule where the stretching of the 

 lower part of the nucellus and the formation of 

 a pseudo-embryo-sac has just begun. The spore 

 mothercell as yet undivided. Mag. x 580- 



Fig. 7. Mourera fluviatiUs. Megaspore in a later stage 

 than that of fig. 5. Two nuclei and a degenerating 

 antipodal nucleus. Mag. x 1000. 



Fig. 8. Mourera fluviatiUs. Egg-apparatus with embryo- 

 sac. The upper cell, which has been formed by 

 division of the spore mothercell with its two 

 nuclei is yet visible; below it we meet fiist the 

 two synergids, then the egg and at last the 

 embryo-sac wirh its nucleus and the degenerated 

 antipodal nucleus. Mag. X 1000. 



Fig. 9. Mourera fluviatiUs. Top of the nucellus with a 

 pollen-tube passing between two cells of the 

 epidermis and fusing with one of the synergids. 

 This synergid is again fusing with the egg, the 



