88 



Yet stages like those pictured in fig. 42, 46 PI. IX, fig. 49 

 Pi. X, fig. 44 Pi. IX, fig. 36 PI. VIII, with one endosperm- 

 nucleus are exceedingly frequent, at this moment the stigmata 

 are present yet, and it seems improbable to me that a pollen- 

 tube or at least the grain belonging to it would have always 

 been overlooked by me. 



I have looked in vain in the litterature for what happens 

 with the polar nuclei in an embryosac of a normal phanerogamic 

 plant if fertilisation is artificially prevented, wether they fuse 

 in such a case or not. It seems to me that this question is of 

 sufficient interest to be followed up preferably with Fritillaria 

 where we know that normally three nuclei make up the 

 endospermnucleus. The subject, it seems to me, would be a 

 good one for a thesis. 



We know of but two instances of Phanerogams which 

 produce embryo's without fertilisation from organs usually 

 formed only after fertilisation. The one is the case of Balano- 

 phora where Tredb showed that the embryo arises apogamically 

 the other one is that of Antennaria alpina ^), a Composit. In 

 both these cases the polar nuclei do not fuse. In the case of Bala- 

 nophora it is the polar nucleus belonging to the eggapparatus- 

 tetrade, a sisternucleus of the eggcell consequently, which 

 alone survives and gives rise to the endosperm , not however 

 without first undergoing division by which two endospermcells 

 arise, the lower one of which dies while the upper one alone 

 forms the endosperm. In the case of Antennaria the polar 

 nuclei do not fuse, but each divides independently and con- 

 tributes to the endosperm -). 



Consequently Rhopalocnemis is apparently able to form a normal 

 endosperm nucleus without fertilisation while Balanophora and An- 

 tennaria are not. 



All trials to fertilize flowers of Rhopalocnemis have been 



1) H. 0. Juel. Bot. Centralbl. 74. p. 369/372. 1898, I regret that Mr. Jtjel does 

 not indicate whether seeds are frequent or rare in this species. 



2) Words quoted from the abstract by Chas. J. Chamberlain in Bot. Gaz. 1899. 

 1. p. 74. 



