266 EXPLANATION OF THE PLATES. 



Fig. 10. Common partition-wall between two cells from fig. 9, 

 under a higher magnifying power. The stratiform 

 depositions may be observed at b, and the porous 

 canals produced by their local failure at «. I could 

 distinctly enumerate, from nine to twelve layers 

 which had been deposited within fourteen days. 



11. A sporule from Rhizina Icevigata Fries, with the 



cytoblast. 



12, 13, 14. Different cytoblasts from the embryo-sac of 



Pimelea drupacea before the appearance of cells. 



15. A young cell with its cytoblast, from the same. The 



latter in this instance presents the unusual number 

 of three nucleoli. 



16. A portion of the emb^onal end of the pollen-tube 



projecting from the ovulum in Orchis Morio, within 

 which, towards the upper part, cells have been 

 already developed. At the lower part, the original 

 pollen -tube may still be distinguished. The almost 

 globular cytoblasts are, in this instance, distinctly 

 enclosed in the cell-wall. 



17. Embryonal end of the pollen-tube from Linum pal- 



lescens, together with an appended lobule of the 

 embryo-sac (a). The process of the formation of 

 cells is commencing. Above, a young cell with its 

 cytoblast is already perceptible, beneath this several 

 cell-nuclei are seen floating free. 



18. 19, 20. Commencing germination in the sporules of 



Marchantia polymorpha. Compare the text, p. 248. 



21. Portions of the pollen-tube which have become cel- 

 lular, from Orchis latifolia, in the highest stage of 

 development; the investment of the pollen-tube is 

 no longer perceptible. The cytoblast is enclosed in 

 the cell-wall, just as in fig. 16. 



22 and 23. Two isolated cells from the terminal shoot 

 (]junctum vegetationis, Wolff) of Gasteria racemosa; 

 22 exhibits two free cytoblasts; 23, two newly- 

 formed cells within the original cell. 



D. H. HILL UBRARY 



North Carolina State College 



