1907] SM/JTH—TRUNK AND MICROSPORANGIUM OF CYCADS 203 
Fic. 11. Section of staminate strobilus of jig. 7, showing the periclinal 
division of a hypodermal cell which is the first stage in the development of a 
sporophyll. X650. 
Fig, 12. Section of staminate strobilus, showing further divisions of hypoder- 
mal cells and layers beneath them to form sporophyll. 650. 
Fic. 13. Longitudinal section of peg raligha elevation of sporophylls 
and rudimentary bundles passing into them. 
. 14. Tangential section of staminate cone of July 25, showing sporo- 
phylls and position of young sporangia. 
Fic. 15. Cross-section of sporophyll of Ceratozamia, showing sporangia. X 37. 
Fic. 16. Cross-section of sporophyll of Ceratozamia, iia grouping of 
sporangia into sori and extension of bundles into them 
Fic. 17. Cross-section of sporophyll of Zamia. X 39. 
Fics. 18, 19. Three sporangia of aoa ‘united” at base. X95. 
Fic. 20. Detail of fig. 19, showing union of sporangia at base. 
Fic. 21. Sporophylls from one cone of Zamia floridana: a, usual sicuunetiend 
of sporangia; 6, sporangia extending to middle region; c, sporangia extending 
across middle region; d, reduced number of sporangia. X2. 
Fic. 22. Sporophyll of fig. 14, showing hypodermal ance cell. Xg20. 
Fic. 23. Division of archesporium by an anticlinal wa 20 
Fic. 24. The periclinal divisions resulting in inner and outer lates of cells. 
XQ20. 
Fic. 25. Archesporial cell in a section parallel to the surface of the sporo- 
phyll. <g20. 
1G. 26. Periclinal division of archesporial cell (exceptional). 920 
Fic. 27. First (anticlinal) division of archesporial cell in a section peralied 
to the surface of the sporophyll. 
Fic. Further periclinal reise succeeding the division shown in jig. 26. 
X9Q920 
Fic. 29. Usual divisions following the stage shown in jig. 24; lower four cells 
of section are sporogenous. X920. 
Fic. 30. Longitudinal section of sporangium in more advanced stage. 920. 
Fic. 31. Longitudinal section of sporangium of Ceratozamia; tapetal cells 
pat by +. 180 
. 32. Longitudinal section of sporangium of Zamia, showing thickened 
aes et apex and band of dehiscence. 95. 
Fic. 33. Detailed drawing of part of sporangium: w, duter wall layers; y, 
two biepane of tabular cells, which are crushed by the activity of the tapetum; ¢, 
—— 5, sporogenous cells. 800 
- 34. Apex of sporangium of Pate: showing thick-walled cells; isodia- 
metric es beneath them. X 580. 
Fic. 35. Diagram of sporangium of Encephalartos. 
Fic. 36. Tangential section through sporangium of Zamia near apex, showing 
fick-wealied cells and line of dehiscence (d). 180 
