EXPLANATION OF PLATES. 



ii .Vntipodal ; lu antipodal cells ; al nleuiDnc; layer : as aicbesporiuni ; 

 ax axis ; c carpel : en cotyledon ; co coleorhiza : cr chromosomes ; 

 ct co-idiicting tissue ; d dyad : dm dermatogen : dn definitive nucleu> ; 

 e- e^-y ; ea egjj apparatus ; em embryo : en endosperm : ep epiblast ; 

 .-v embryo-sac ; et endotbecium ; fm functioning niegaspore : fn female 

 nucleus; ^n generative nucleus : gp germ pore : h hypocoty! ; / integu- 

 ment ; ip inner palea : / lodicule : //"leaf: m microsporangium ; me 

 microspore mother-cell ; nid megaspore dyad : me megasporangium ; 

 mm megaspore motlier-cell ; mt megaspore tetrad ; mp micropyle ; 

 n nucleus : ne nucellus : ns nuclear spintlle : up outer palea ; oii> ovary 

 wall; / pollen grain ; /(?' periblem ; // plerome ; pp primary parietal- 

 cell ; ps primary sporogenous cell ; pt pollen-tube : r root ; s stem ; 

 sg synergitl ; sr suspensor ; st stigma : / tetrad ; tn tube nucleus ; 

 tp tapetnm. 



PLATE L 



Fig. I . Sketch of a wheal dower. 



2. Floral diagram sketch. 



3. Longitudinal section of a grain, showing embrvo and endosperm. 



4. Developing seedling. 



V .Soriis of young Microsporangia in transverse section, v 445. 

 b. Dividing archesporial cells. < 44^ 



7. Transverse section of a Microsporangium showing wall layers. 



. < 445- 



8. Microspore mother-cells free in the loi ulus, synapsis. 

 '). Microspore mother-cells dividing. 



10. Dividing Microspore mother-cells showing chromosomes, x 687. 



11. Pollen grain of wheal showing vegetative nucleus and two 



generative nuclei. x 445. 

 I ra. Do. do. o( Seeale eereale rye (after Golinski). 



12. Section of nucellus showing archesporium. x 533. 



13. Dyad archesporium. X ^53. 



14. Tetrad of megaspore mother-cells. \ 533. 



15. Inner functioning megaspore. 



It). Archesporium with apical non-nuclealed cvtoplasm. 



PLATE IL 



17. Transverse section of Ovule showing closlv appressed integu- 



ment layers. 



18. Spitidle ^x 1 125) and Telophase (x 445) Mitoses in l^rst 



division of embryo-sac cell. 



19. Four-celled embryo-sac. x 445. 



20. Ten-celled embryo-sac. x 300. 



21. Antipodal cells (x 183) with plate-like conlents. x 687. 



22. Germinating pollen grain on a stigma branch, x 183. 



-3- EgJJ apparatus pressing open the micropvle to admit pollen- 

 tube, x 183. 



24. Course of pollen-lube in the ovarv 



25. Pollen-tube lying within a synerg'id. x 183. 



26. Fertilised egg. 



27. First segmentation of the fertilised egg. 



28. Longitudinal section of an embryo-plate of six cells, x 445. 



29. Older embr5-o showing differentiation of parts, x 183. 



