XV 



THE DEVELOPMENT OF THE FLOWER 



203 



The large cell which we may call the embryo-sac continues to 

 grow, and its nucleus, that is, it must be remembered the prim- 

 ary embryo-sac nucleus divides and the two daughter 

 nuclei move to the ends of the embryo-sac. They both divide 

 again. There are thus two at each end of the sac. These again 

 divide, so that there are eight nuclei in the embryo-sac, four near 

 each end. The protoplasm now forms around three of the nuclei 

 at each end. The three at the end nearest the micropyle form 

 the egg-apparatus, and those at the opposite end the antipodal 

 cells. One nucleus from each end passes towards the middle of 

 the sac. These unite and form the secondary embryo-sac 

 nucleus. 



Kinds of Ovules. There are three common types of ovules, 

 and the names which they receive depend upon the relative posi- 

 tions of the funiculus and body of ovule. These are explained 

 by the figures given. They are as follows : 



i. The ovule is Orthotropous (atropous) when the funiculus 

 and the axis of the ovule forms a continuous line (Fig. 209, A). 



Fig. 209. Diagrams of Ovules. A, orthotropous ; B, anatropous ; C, campylotropous. 

 (After Strasburger.) 



The nucellus is then straight, and the micropyle is at the greatest 

 possible distance from the funiculus. 



2. The ovule is Anatropous when the funiculus curves sharply, 

 so that it lies side by side with the body of the ovule. (Fig. 209, B). 



3- The ovule is Campylotropous when the ovule is itself 

 curved so that the micropyle and the chalaza, or basal portion of 

 the ovule, do not lie in the same straight line. (Fig. 209, C). 



