XVI] 



APOGAMY AND APOSPORY 



325 



Fig 302. Neplirodiuiii pscudo-nias,vixx. polydactylttiii. Tissue of pro- 

 thallus where an apogamous growth is to be found, showing on 

 the left a cell with two nuclei, while an adjoining cell has none. 

 At the centre a nucleus is seen passing through a perforation of 

 the wall, and fusing immediately with that of the cell it enters. 

 (After Farmer, Moore, and Miss Digby.) 



further from the normal cycle than the previous case. The chromosome- 

 numbers for the two generations are 16 and 32 respectively, and normal 

 plants show the usual succession of 

 events. But on germination of the 

 megaspores borne by certain plants 

 the gametophyte was found to have 

 the diploid number, and this was seen 

 even in the division to form the ventral- 

 canal-cell of the archegonium ; thus the 

 ovum itself was diploid. In such arche- 

 gonia the neck does not open, so that 

 fertilisation by spermatozoids is im- 

 possible (Fig. 303). Nevertheless the 

 unfertilised diploid &^g develops apo- 

 gamously into an embryo, which is 

 naturally diploid also. An examination Fig. 303. Marsilia Dnmunondii. Partheno- 



Of the sporangia showed further that genetic embryo: the neck of the archegonium 

 ^ ^ _ has not opened, and the ventral-canal-cell 



while in typical Marsilias the reduction {v.c.c.) is still in place. (After Strasburger.) 



