1919] DUPLER—TAXUS 365 



EXPLANATION OF PLATES XXIV-XXVI. 



All drawings were made with a camera lucida; text figs, i-io and 13-22 

 are drawn to the same scale, with a magnification in reproduction of approxi- 

 mately 36; text figs. 11-12 and all plate figs, are drawn to the same scale, 

 reduced one-half in reproduction, having a magnification of approximately 475. 



PLATE XXIV 



Fig. 2T,. — Young sporophyll primordium, showing 2 archesporial initials 

 in hypodermal layer of rounded primordium. 



Fig. 24. — Archesporial initial in hypoderm; division of epidermal cell. 



Fig. 25. — Archesporial initial in tangential section. 



Fig. 26. — Archesporium of 2 cells. 



Fig. 27. — Metaphase in division of archesporial initial. 



Fig. 28. — Late stage in division of archesporial initial. 



Fig. 29. — Primary wall cell (outer cell) and primary sporogenous cell 

 (inner cell), resulting from division of initial. 



Fig. 30. — Primary wall cell and division of primary sporogenous cell. 



Fig. 31. — Primary wall cell has formed 2 tiers of wall cells, in one of 

 which division is taking place; primary sporogenous cell has divided anti- 

 clinally, forming 2 sporogenous cells. 



Fig. 2,^. — Lobe of young sporophyll, showing small mass of sporogenous 

 tissue, 2-layered sporangium wall formed on outer side, and meristematic basal 

 portion of epidermis differentiated from remainder of epidermis. 



Fig. ^i. — Somewhat older stage than fig. 32. 



Fig. 34. — Sporangium wall complete, entirely surrounding sporogenous 

 mass; latter part of July. 



Fig. 35.— Older sporangium, showing differentiation of tapetum from 

 sporogenous tissue. 



Fig. 36. — Portion of sporophyll, showing epidermis, 2-layered sporangium 

 wall with narrow flat cells, tapetum (i cell binucleate), and microspores; 

 winter condition. 



PLATE XXV 



Fig. 37. — Transverse section of portion of lower scale, showing stoma on 

 inner surface and heavily cutinized epidermal walls, especially on outer surface. 



Fig. 38. — Transverse section of portion of upper scale, showing vascular 

 bundle and inner epidermis of scale ; in vascular bundle note centripetal xylem 

 and 2 transfusion cells, i dorsal, i lateral to xylem. 



Fig. 39. — Transverse section of bundle a of fig. 13, showing phloem char- 

 acter of bundle; no xylem present. 



Fig. 40. — Bundle a at level of fig. 15, showing mesarch character. 



Fig. 41. — Bundle e of fig. 15; single xylem cell surrounded by phloem. 



