5c8 



PHANEROGAMS. 



vesicles would correspond to the essential contents of an archegonium such as that 

 of Salvinia ; the lower rounded part which subsequently developes would be the 

 oosphere, and the upper appendage the canal-cell, which is in this case only 

 separated from the former after impregnation. The very rare occurrence of the 

 filiform apparatus in Angiosperms can scarcely be brought forward as an objection 

 to the explanation; since in this case, as in the 'antipodal cells,' we have to do 

 with an organ which has become rudimentary, and the occurrence of such organs 

 is commonly observed to be very variable and inconstant. In the enormous 

 majority of Monocotyledons and Dicotyledons the filiform apparatus of the em- 

 bryonic vesicles is wanting, the number of these latter being almost invariably two, 

 rarely three. They usually lie obliquely one over the other, one closely attached 

 to the apical prominence of the embryo-sac, the other situated lower down and 

 sideways, but adpressed to the former by its bit)ad surface ; both adhering by their 

 peripheral end to the wall of the sac. The fertilising pollen-tube usually, as Hof- 



FlG. -^.—Futikia cordata ; A apex of the embryo-sac e, covered with a layer of cells belonging to. the nucleus KK, x the 

 embryonic vesicle which is incapable of fertilisation, o the peculiarly shaped 'oosphere' with its nucleus ; B, C 'oosphere' 

 before, D, E after the first division ; F the spherical pro-embryo with the two-celled rudimentary embryo (Xsoo). 



meister's and Schacht's drawings show, perhaps always, m.eets the apical embryonic 

 vesicle (Fig.368,^, ji'); but this does not then undergo further development, but dis- 

 appears, while the one which lies lower down and at the side (0), and which is not 

 touched at all by the pollen-tube, produces the pro- embryo, and subsequently the 

 embryo. It appears therefore as if one of the two embryonic vesicles assume the 

 function of the filiform apparatus or the canal-cell, while the other represents the 

 oosphere. Sometimes even one embryonic vesicle is decomposed before impregna- 

 tion takes place, as in Funkia cordata (Fig. 368) ; it resembles a lump of tough 

 granular mucilage. Judging from Hofmeister's drawings, something of the same 

 kind appears to occur also in other cases. In any case it is only one of the em- 

 bryonic vesicles — that which produces the embryo — which can be looked on as the 

 oosphere, since the other one, not merely occasionally but normally, has nothing to 

 do with the formation of the embryo ; its essential function appears to be merely 

 to transmit the fertilising substance from the pollen-tube to the embryonic vesicle 

 which is destined for further development. This remark refers however only to 



