32 MINNESOTA BOTANICAL STUDIES. 



Explanation of Plates. 



Plate IV. Figure i. Young ovule about three weeks before the flower- 

 ing period. Mcgaspore mother-cell in synapsis. X 400. 



2. Injier part of ovule a few days after flowering, showing one-celled 

 embryo, developing endosperm, including the peculiar antipodal portion, a, 

 the nucellar remains n, n , the inner integument, x, and part of the outer in- 

 tegument, o. X 290. 



3-9. Early stages in the development of the embryo. X 950. 



10. Antipodal end of embryo-sac of a seed about three weeks after 

 flowering, showing the relation of the structures of the embryo-sac to the 

 chalazal vesicle. X 300. 



Plate V. Photomicrographs of the embryo. 



11. Micropylar end of the embryo-sac about one month after flower- 

 ing, showing small embryo. X 200. 



12. Embryo in seed about seven weeks after flowering showing the 

 beginning of the cotyledonary mounds. X 100. 



13. Slightly older embryo. X 100. 



14. Embryo with well developed cotyledons, about two months after 

 flowering, showing differentiation of plerome, periblem, root-cap, and epi- 

 cotylary meristem. X 100. 



15. Longitudinal section, perpendicular to the plane of the cotyledons, 

 of an embryo from a nearly ripe seed, three months after flowering, — r^ 

 growing point of the root, c, epicotylary meristem. X 50. 



16 and 17. Two longitudinal sections of an embryo from a ripe seed, 

 taken parallel to the plane of the cotyledons, s, stomata, e, as in fig. 15. X 50. 



18. Embryo from seed which had germinated for fourteen months. X 50. 



Plate VI. Seedlings of the first year's extra-seminal growth. — Photo- 

 graphs, natural size. 



19 and 20. The usual method of germination. 



21. Same seedling as fig. 19 with part of the seed removed to show 

 the haustorial part of the cotyledons. 



22. Same seedling as fig. 20 removed from seed. 



23. Unusual type of germination in which a foliage leaf is developed the 

 first year. 



Plate VII. Seedlings of the second year's extra-seminal growth. — 

 Photographs, natural size. 



Plate VIII. Seedlings of third and fourth year's growth. X 2I i. 



Plate IX. Seedling about ten years old, showing the .still functional 

 primary root, the development of secondary roots from the rhizome, and 

 the branching of the rhizome. X Y^. 



Plate X. Photograph of reconstructed models of embryos at about the 

 age shewn in figs. 12 and 13. Plate V. X 100. 



