ANGIOSPERMS. 



33 



with the cells of the layer next beneath it, or sometimes even those of deeper-lying 

 layers, arches outwards to form the protuberance ; the ovule is never formed from 

 superficial cells, as is the case with the sporangia of many Vascular Cryptogams. The 

 apical portion of the protuberance becomes the nucellus, the basal the funicle 

 (sporangium-stalk). Then the integuments begin to grow from beneath the nucellus, 

 and an annular wall is formed which grows up completely over the nucellus ; if a 

 second and outer integument is added to the first, it is formed in a similar manner 



(V til 



FIG. 316. Orchis militaris. Development of the ovules, magn. 550 times ; successive stages shown in the order of 

 the numerals / to VII. VIII is a transverse section of /. / VI are side views and in optical longitudinal section. VII 

 is a front view and the funiculus is behind. The letters xx denote the axile cell-row, the upper cell of the row being the 

 mother-cell of the embryo-sac e (the archesporium),ythe funiculus, 11 the inner, to. and a;' the outer integument, A' the 

 nucellus, ts the micropyle, h an intercellular space; in -'// the embryo-sac e has entirely displaced the tissue-layer of 

 the nucellus. 



from beneath the first and grows over it. Terminal ovules usually continue straight 

 (orthotropous) ; those which are afterwards anatropous appear at first as a straight or 

 only slightly curved projection, but soon become distinctly curved at the spot where 

 the first or the only integument originates (Fig. 316 //, ///, IV); the apical part 

 which is enclosed by the integuments forms the nucellus, while the basal portion 

 beneath them is the funicle. As the integuments develope the curvature increases, 

 and the nucellus is at length inverted even before the outer integument is quite 

 formed, and consequently the latter does not develope on the side of the ovule which 

 is towards the raphe but spreads over the free parts of the ovule, growing up to the 



