Prof. C. Morren on the discoid Piths of Plants. 87 



Fig, 6. Cells seen from the top of the disc in Begonia argyrostigma. 



a. Folds. 



h. Globules. 

 Fig. 6 his. Bud of Juglans regia cut open longitudinally. 



a. Derm. 



b. Mesophloeum. 



c. Ligneous system. 



d. Medullary discs. 



e. Compact pith. 



/. Pith of the terminal bud. 



g. Scar of the leaf. 

 Fig. 7. Branch of Juglans with very compact pith. 



A. Bud corresponding to the 

 a. Medullary cavities. 



h. Other medullary cavities. 



c. Compact pith. 

 Fig. 8. Old dead branch of Juglans regia. 



a. Derm. 



b. Mesophloeum. 



c. Ligneous system. 

 ^. Medullary discs. 



e. Roots of these discs. 

 /. Medullary cavities. 

 Fig. 9. Isolated disc, much enlarged, taken from an old branch. 



A. Root of the disc. 



B. Disc. 



a. Empty cells. 



b. Crystalliferous cells. 



c. Mass of resinous matter. 

 Fig. 10. Discs o{ Jasminum fruticans. 



a. Cells which are void. 



b. Fecule 



c, d. Cells still replete with fecule. 

 e, /, g. Discs with empty cells. 

 Fig. 11. Branch of Jasminum fruticans. 

 Fig. 12. Section of the stalk of Phytolacca decandra. 



a. Derm. 



b. Mesophloeum. 



c. Wood. 



d. Medullary discs. 



e. Empty spaces. 

 Fig. 13. Cells of the discs. 



a. Cells. 



b. Folds. 



c. Globules. 



d. Clusters of crystals. 



