PLATE 38.— Vegetable Tissues. 



Figure 



1 . Embryo-sac and supporting cells, of Orchis morio. 



2. The same, more advanced. 



3. The same, with a germinal vesicle at its apex. 



4. The same, with three germinal vesicles, just before impregnation. 



5. The same, after the pollen-tube {p t) has reached it ; one of the germinal vesicles 



(e) already being developed to form the embryo. 



6. The same, more advanced, showing the first cell of the suspensor (s) at the upper 



end. 



7. Embryo-sac of Lathrcea Squamaria before the origin of the germinal vesicles ; 



p, amorphous protoplasm ; e, protoplasm in course of development into endo- 

 sperm-cells. 



8. 9. Apices of very young hairs of the filaments of Tradescantia virginica ; n, n, 



nuclei, containing nucleoli ; p, protoplasm. 



10. Cylindrical cell from which are formed the parent-cells of the spores of Marchantia 



polymorpha ; p, primordial utricles of the parent-cells. 



11. The same, converted into a string of cells. 



12. One of the parent-cells isolated, with four primordial utricles of the spores. 



13. The four spores free. 



14. Transverse section of pith and internal wood of elder ; d, porous duct. 



15. Epidermis of the leaf of the pine-apple, seen from above. 



16. Vertical section of cork. 



17. Transverse section of ditto. 



18. Transverse section of stellate parenchyma of rush-pith. 



19. Cellular tissue (parenchymatous) of the leaf of Orthotrichum pulchellum. 



20. Cellular tissue (prosenchymatous) of the leaf of Hi/pnum decipiens. 



21. Section of the albumen of the seed of Areca Catechu. 



22. The same, after treatment with sulphuric acid and iodine. 



23. Section of the bony albumen of vegetable ivory, a, cells and pits filled with air; 



c, cells filled up with Canada balsam. 



24. Cell-membrane of Hydrodictyon utriculatum. m, the laminae of the cellulose 



coat ; Pi protoplasm. 



25. Vertical section of the epidermis of a misletoe-branch several years old. 



26. The same, after boiling in solution of potash and treatment with iodine. 



27. Transverse section of a liber-cell of the oak, after long boiling in nitric acid and 



treatment with iodine. 



28. Vertical section of the upper face of the leaf of Cycas revoluta. a, cuticle, 



extending over the epidermal cells, which, like the deeper-seated cells, have 

 pitted secondary deposits. 



