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1904] CHRYSLER—CENTRAL CYLINDER 183 
13. Scott, R., and SarGant, E., On the development of Arum maculatum from 
the seed. Annals of Bot. 12:399-414. pl. 25. 18098. 
16. VANTIEGHEM, Pu., Recherches sur la structure des Aroidées. Ann. Sci. 
Nat. Bot. V. 6:72-210. pls. I-10. 1 
, Sur la polystélie. Ann. Sci. ‘Nat. Bot. VIL. 3:275-322. pls. 13-15. 
886. 
17. 
EXPLANATION OF PLATES XII-XV. 
PILATE ATI. 
Fic. 1. Acorus Calamus; section through stele at point of exit of traces of 
third leaf. X go. 
Fic. 2. Same; part of mature stem: 6, bundle in process of division into leaf 
trace and medullary bundle; g, gap through which a leaf trace has recently passed; 
¢, cortex; m, medulla. x 
Fic. 3. Same; central cylinder from base of flowering axis. X 35. 
Fic. 4. Symplocarpus foetidus; section through basal oa of tuber. X 15. 
Fic. 5. Same at region of the cotyledonary gap (g). 
Fic. 6. Same a short distance higher up; ee va closed. X 25. 
PLATE XII. 
IG aioli joetidus; specimen showing early degeneration of 
internal hildactenn < 36. 
Fic. 8. Same; region above closure of the cotyledonary gap. 
Fic. 9. Peltandra virginica; general view showing cotyledon a ae sepa- 
rated off; 7, r, secondary roots. X 7.5. 
Fic. 10. Same; basal region of seedling. X 30. 
Fic. 11. Same; region of cotyledonary gap; r, secondary root. X 25. 
_ Fic. 12. Same; cotyledonary gap closing. X 25. 
PLATE XIV. 
Fic. 13. Clistonis borealis; stele of eee rhizome. X 25. 
Fic. 14. Part of section shown in fig. 13. 5 
Fic. 15. Clintonia umbellata; stele of ue rhizome. X 20. 
Fic. 16. Maianthemum bifolium; stele of mature rhizome shortly above 
region at which it turns upwards. X age 
Fic. 17. Same at the second node. 5 
Fic. 18. Smilacina stellata; stele in . second internode. X 125. 
PLATE XV. 
Fic. 19. Smilacina stellata; higher region of seedling; m, bundle which has 
eft periphery of stele to run for a distance in the medulla; #, leaf trace. X 65. 
