1905] SHATTUCK—ULMUS AMERICANA 
Fic. 51. Embryo sac showing two embryos nearly the same age. 500 
Fic. 52. Embryo sac showing two embryos; one much older. 800 
Fic. 53. Embryo sac showing unusually large antipodal. x 810 
Fic. 54. Large embryo sac showing fifteen nuclei, the central one probably 
the fusion nucleus; a large egg-like antipodal. x 1200. 
Fic. 55. Double embryo sac showing in one sac nine, and in the other twelve 
nuclei; no egg apparatus organized. 1200 
Fic. 56. Double embryo sac ails egg i apearetan ——— in the opposite 
ends. X 1000. 
Fic. 57. Fusion of two polars. X 1000. 
Fic. 58. Fusion of three polars. 1000 
Fic. 59. Fusion of four polars. 1000 
Fic. 60. Second mitosis of the binucleate sac. x 400 
