DEVELOPMENT OF EMBRYO IN CAPSELLA. 413 



synergidae, and an oosphere, in the egg-apparatus, while the 

 antipodal cells are very difficult to see. We can see that the 

 fertilised oosphere (oospore) grows into a thread-like pro-embryo, 

 about six cells long, of which the uppermost cell, i.e., that most 

 removed from the micropyle, rounds off into a spherical embryo- 

 cell, and the other cells collectively form the suspensor, while 

 the lowermost cell of this embryo-bearer or suspensor, the attach- 

 ing-cell, swells at the same time bladder- wise, absorbs the entire 

 nucellar tissue up to the integument, and forms the bladder 

 which we find at this place even in the ripe stage (compare Fig. 

 149, A, at the. tip of the radicle). This swollen cell may aid 

 in the absorption of nutriment or the embryo. The spherical 

 embryo-cell is already at this stage separated from the suspensor 

 by a partition wall, and soon after is divided by a longitudinal 

 wall, at right angles to which follows a second longitudinal wall, 

 and then at its mid-height a cross-wall. The still spherical 

 embryo thus appears divided into octant cells, in which are 

 subsequently formed periclinal and anticlinal walls. The embryo 

 increases in size and in number of constituent cells, flattens some- 

 what, and then from its anterior end the cotyledons grow T out. 

 These at first are in contact at their base, and then subsequently 

 the growing point or plumule of the stem bulges out between 

 them. All of these stages can likewise be followed in fresh 

 material, and in situ, by laying the ovules in glycerine, covering 

 with a cover-glass, and then carefully heating over a spirit or gas- 

 flame. The ovule is thus made transparent, and the embryo 

 clearly visible. By careful use of the potash method of treatment^ 

 and cautious pressure upon the cover-glass with the needles, even 

 the youngest embryos can be squeezed out from the ruptured 

 ovules, though in this method the relations of the embryo with 

 the ovule are, of course, lost sight of. 



Monocotyledonous Seed of Alisma. For the study of the 

 monocotyledonous embryo we select the common water plantain, 

 Alisma Plantago, which, like Capsella, is highly suited to this 

 kind of investigation. We will here restrict our study to the 

 fully-developed state. The flower of Alisma Plantago contains 

 numerous monocarpellary pistils ; it is apocarpous, resembling 

 in this respect the Eanunculacese. The ripe carpels of the flower 

 are closely pressed together in a single whorl into a collective 

 or aggregate fruit a dry etserio of triangular outline. Each in- 

 dividual ripe carpel (achene) is strongly flattened laterally, some- 



