13 



non in Podostevnaceae seems to me to prove, that 

 there are causes acting in tlie ovule, which faveur 

 the development of such a large cavity as tlie embryo- 

 sac, so that in those cases, in which the embryo-sac îtself 

 does not develop greatly, because it is enclosed and sepa- 

 rated off in the upper part of the ovule, the cavity is 

 formed by other cells, lying underneath the embryo-sac. 

 3. The development of the embryo-sac départs widely 

 from the normal, in that no antipodal cells and no antipodal 

 polar nucleus are formed, on account of the early degenera- 

 tion of the nucleus, which, by its divisions should hâve 

 given rise to thèse nuclei. Further more, after the egg- 

 apparatus has been formed, the remaining portion of the 

 embryo-sac is' only very slightly developed, so that there 

 is no question of the formation of endosperm (what hap- 

 pons to the second generative nucleus, if indeed présent, 

 I hâve not been able to make out). It is much clearer 

 hère than in most cases, that this portion of the embryo- 

 sac and the egg-cell are sister-cells. This agrées with the 

 View of Porsch^), according to whom the egg-apparatus 

 of the higher plants is a reduced archegonium, the syner- 

 gids being the neck canal-cells and the upper part of 

 the embryo-sac with the upper polar nucleus being the 

 ventral canal-cell. The latter hypothesis is however speci- 

 ally difficult in this case, for hère the positions of egg- 

 cell and of ventral canal-cell would be exactly reversed. 

 A réduction in the antipodal apparatus, similar to that 

 which occurs hère, is found in Helosis guyanensis, accor- 

 ding to the investigations of C h o d a t and B e r n a r d '^), and 



1) 0. P o r s c h. Versiich einer phylogenetischen Erklarung 

 Embryosackes und der doppelten Bel'ruchtung der Angiospermen. 

 Jena 1907. 



2) R. Chodat et C. Bernard. Sur le sac embryonnaire de 

 l'Helosis guyanensis. Journal de Botanique. T. XIV. 1900, p. 72. 



