202 BOTANY FOR BEGINNERS CHAP. 



antipodal cells, which consist of three cells which are placed at 

 the posterior end of the embryo sac. In many cases these 

 disappear before the ovule is ready for fertilisation, (iv) The 

 granular protoplasm, in which the above structures are em- 

 bedded, (v) The vacuole, which is filled with cell-sap. 



The funiculus unites the ovule to the wall of the ovary and con- 

 tains a vascular strand which carries the nutritive materials neces- 

 sary for the development of the ovule and embryo or young plant. 

 The integuments protect the nucellus and embryo-sac from injury. 

 In a few plants the integuments may not be developed. The 

 most important part of the ovule is the embryo-sac with its 

 contents. 



EXPT. 184. Cut transverse sections through the open flower of the 

 Marsh Marigold. Wash the section from the razor with water into a 

 watch-glass. Mount a section containing ovules in dilute glycerine. 

 Examine under a low power. Note 



(i) The ovules connected to the carpel by short stalks the funicles. 



(ii) The embryo-sac, which is very large. 



Examine the embryo-sac under a high power. Note 



(iii) The egg apparatus, which consists of synergidoe and oosphere. 



(iv) The antipodal cells at the far end of the embryo-sac from the 

 micropyle, 



(v) The embryo-sac nucleus. 



~~ The Development of the Gyncecium : The gyncecium 

 is the last part of the flower to appear, and it always occupies 

 the apex of the floral axis. The carpels may be separate as they 

 are developed and afterwards unite, or they may remain separate 

 (as in an apocarpous gyncecium). (p. 186). The zone of tissue 

 just below the carpels begins to develop and carry up the carpels 

 with it. The union of the carpel or carpels forms the ovary. 

 Ridges appear on the wall of the ovary. These are the placentas 

 from which the ovules will be developed. 



The Development of the Ovules. The ovules are formed 

 as outgrowths of the placentas. Each ovule at first consists of 

 two layers of cells belonging to the epidermis of the wall of the 

 ovary, and to a deeper layer just below it. One cell is larger 

 than its neighbours and from this the embryo-sac and its contents 

 are formed. The integuments and the nucellus are formed from 

 the cells at the base of the projection. The funicle is also formed 

 from the cells at the base of the ovule and fixes it to the 

 placenta. 



