Lyon : THE EMBRYOGENY OF GINKGO. 289 



entiation of tissues and shape of meristems. The secretory canals are 

 black. The openings in the cortex are resin-reservoirs. 



PLATE 34. 



13-17. Sections taken at intervals from a series of cross-sections 

 of a dicotyledonous embryo (x 28). 13, through root-meristem ; 

 14, through transition-region; 15, through bases of cotyledons; 16, 

 through cotyledons and stem of plumule; 17, through cotyledons and 

 plumular leaves. 



18, 19. Sections of a tricotyledonous embryo (X 28). 



20. From an embryo showing a condition intermediate between a 

 typical dicotyledon and tricotyledon ( X 28). 



21. A section near the tips of the cotyledons of a tricotyledonous 

 embryo, two cotyledons of which developed conjointly (x 28). 



PLATE 35. 



22-29. Embryos removed from seeds grown in Japan (x 5.5). 

 The dark knobs, very prominent on some of the embryos, are pro- 

 truding resin-reservoirs. 



PLATE 36. 



30-37. Embryos removed from seeds grown in the Missouri Bot- 

 anical Garden (x 5.5) Figs. 36 and 37 are cases of true twinning; 

 two metacorms having developed from one protocorm in each case. 



PLATE 37. 

 38-46. Young Ginkgo seedlings about natural size. 



PLATE 38. 



47. A young seedling which has just completed its growth in 

 length for the first season, slightly reduced. 



48. A seedling at the end of its first season's growth, somewhat 

 reduced. 



PLATE 39. 



49. A young plant early in its second year, somewhat reduced. 



PLATES 40 AND 41. 



50-57. Sections, selected at intervals from a series, passing from 

 the root through the transition-region to the stem of a young seedling 

 (X 92). 



PLATE 42. 



58, 59. Sections of a cotyledon of the seedling shown in Fig. 48 

 (X 28). Fig. 58 is through the petiole, and Fig. 59 through the 

 thickest portion of the cotyledon. The circular openings in Fig. 58 

 are resin-reservoirs. 



