346 Mr. A. Henfrey on the Progress of Physiological Botany : 



nuclei sen nuclei). The orifice of the latter is directed toward the 

 base of the pro-embryo. 



" Before the formation of the nuclear papilla, there arises at the 

 bottom of the cavity for the embryo-sac a minute transparent 

 cell, the embryo-sac. This is seated like a tubercle on a parti- 

 cular point as its suspensor. Already at this period we find in 

 the cavity containing the embryo-sac from two to five, or even 

 more free spiral filaments, never inclosed in their cellules. For 

 at this period the spiral filaments move by the help of their cilia 

 from the burst spiral-filament organs to the cavity for the em- 

 bryo-sac, and penetrate into it. In this motion they are assisted 

 by the mucus evacuated with them, and by the moisture always 

 present on the under side of the pro- embryo. It requires some 

 acquaintance with the form and different positions of the spiral 

 filaments to recognise them in the cavity. The still wide open- 

 ing of the cavity at this period facilitates their entrance (the 

 borders of the organ scarcely project yet above the surface of the 

 frond). At this period of the impregnation it sometimes hap- 

 pens that we notice a quantity of dead spiral filaments around 

 the cavity of the nucleus ; they then appear curved like an S, or 

 else wound circularly or spirally. But I have seldom observed 

 this phenomenon. As the embryo-sac grows and thus displaces 

 the spiral filaments, the canal of the papilla of the nucleus is 

 formed, in the manner above described, and receives into it one, 

 two or more, rarely several of them ; the rest decay in the bottom 

 of the cavity. Before their entrance into it they exhibit with ad- 

 vancing growth an evident expansion, which occurs especially in 

 those subsequently received into the canal. In the mean time 

 the embryo-sac, filled with blastema, has produced in its interior 

 a parenchyma composed of several cells (endosperm), appears 

 green, and has advanced so much in growth that it almost fills 

 the cavity in which it is contained. One of the spiral filaments 

 penetrates by one end into the part of the embryo-sac turned 

 toward the canal. The penetrating end is that at which the 

 smaller enlargement exists, which at the same time exhibits a 

 greenish tint ; the larger, clavate, granular end projects out into 

 the canal ; this usually incloses a minute pyriform cellule. An 

 obstacle of no slight importance interferes with the observation 

 here also ; the delicate filiform connection of the two ends of the 

 spiral filament is usually torn by the pressure of the covering 

 glass upon the preparation, and thus we see only the separated 

 ends, one in the canal, the other in the cavity for the embryo- 

 sac, totally unconnected. As soon as the smaller expansion has 

 reached the middle of the embryo-sac, it separates from the 

 spiral filament and now forms a closed globule, the germinal 



