288 BOTANICAL GAZETTE [APRIL 
11. Lawson, A. A., Fertilization and embryo of Cryptomeria japonica. Annals 
of Botany 18: 417-444. 1904. 
12. MoprtewskI, J., Zur Embryobildung von Gunnera chilensis. Ber. Deutsch. 
Bot. Gesell. 26:550-556. 1908. 
13. SCHAFFNER, J. H., Contribution to the life-history of Sagittaria variabilis. 
Bot. GAZETTE 23:252-273. 1897. 
14. SmirH, R. W., A contribution to the life-history of the Pontederiaceae. 
Bot. GAZETTE 25:324-337. 1898. 
15. Wy1tk, R. B., The morphology of Elodea canadensis. Bot. GAZETTE 37: 
I-22. 1904. 
. York, H. H., The embryo sac and embryo of Nelumbo. Ohio Nat. 4: 
167-176. 1904. 
Dl 
a 
EXPLANATION OF PLATES XIX AND XX 
the figures were drawn with the aid of an Abbé camera and a Leitz micro- 
scope, and have been reduced one-half in reproduction. The reference letters 
are as follows: 6, bract; s, sepal; p, petal; a, stamen; ¢, carpel; /, tapetum; 
n, apex of nucellus, 
Fic. 1.—Longitudinal section of staminate flower. 105. 
Fic. 2.—Longitudinal section of pistillate flower. X 105. 
Fic, 3a.—Transverse section of staminate flower. X 105. 
Fic. 3b.—Transverse section of same flower at the level of the origin of the 
stamens; /, petals and gland. X 105. 
Fic. 4.—Transverse section of pistillate flower. 105. 
Fic. 5.—Superficial view of pistillate flower with bract (0), sepals (s), and 
petals (p) removed; ovules and apex of flower axis seen through the ovary wall. 
X80. 
Fic. Si Tinta section of a microsporangium at the mother cell stage. 
30. 
Fic. 66.—Part of longitudinal section of microsporangium of same age as the 
preceding. 730. 
Fic. 7.—Section of mature microspore. 730. 
Fic. 5 .—Surface view of mature microspore. 730. 
Fic. 9.—Longitudinal section of ovary with archesporium. X73°- 
Fic. 1o.—Same at older stage. X 730. 
Fic. 11.—The four megaspores. X 730. 
Fic. 12.—Germination of megaspores. X 730. 
Fics. 13-17.—Successive stages in development of embryo sac. *730- 
Fic. 18.—Definitive nucleus before fertilization. 730. 
Fic. 19.—Proliferation into the base of the embryo sac. 730. 
Fic. 20.—Egg apparatus and entrance of pollen tube. * 730. 
Fic. 21.—Egg apparatus after fertilization. X 730. 
Fic. 22.—Fusion of second male nucleus with definitive nucleus. X730- 
