THE CARPEL AND OVULE 



295 



antipodal group [ant.) } and it occupies the base of the embryo-sac, just 

 above the chalazal ending of the vascular strand. At the micropylar 

 end is another group of three cells, called the egg-apparatus (e.a.). One 

 of the cells projects further into the cavity than the other two : it is the 

 Ovum, or egg-cell which after fertilisation initiates the new germ. The 

 other two, called the Synergidae, are of equal size, but smaller than the 



Fig. 216. 



Median longitudinal section of an ovule of Caltha, at the period of fertilisation. 

 /=funiculus. cA=chalaza. o.t'n<=outer integument, i. in*=inner integument. 

 «wc = nucellus. m=micropyle. e. a = egg-apparatus, ant = antipodals. /.n. = fusion 

 nucleus. ( x no.) 



ovum. The egg-apparatus is attached just below the micropyle. 

 In Caltha two layers of cells are seen to intervene (Fig. 216, nuc), but in 

 other plants the number may be larger ; on the other hand in many 

 ovules the embryo-sac is found to abut directly on the micropyle. 

 The large cavity of the embryo-sac is filled by vacuolated cytoplasm, 

 while in the centre the large fusion-nucleus (/.».) with a prominent 

 nucleolus is suspended by cytoplasmic threads. Though ovules of 

 Flowering Plants may vary in form, in the complexity of their 



