June, 1905.] Embryo Sac and Embryo of Batrachium. 359 



DESCRIPTION OF PLATES. 



For the drawings a Bausch and Lomb camera lucida and 

 microscope were used with oculars 2, 1 and 3'' and objectives 

 2-3, 1-6 and 1-12; Figs. 1,8-11, 16-24, 26, 28, 30, 34, 36, 38 and 

 39 were drawn under the 1-inch ocular and the 1-6 objective; 

 Figs. 2, 3 and 37 with the 2-inch ocular and the 1-6 objective; 

 Figs. 4, 5 and 25 with the 3^-inch ocular and the 2-3 objective; 

 Figs. 6, 7 and 14 with the l^-inch ocular and the 1-6 objective; 

 Fig. 12 with the Ij-inch ocular and the 1-12 objective; Fig. 13 

 with the 1-inch ocular and the 1-12 objective; Figs. 29 and 33 

 with the 2-inch ocular and the 2-3 objective. 



Fig. 1 — Section of the receptacle showing two stages in the development 

 of the carpels. 

 -Section of young carpel showing the lamina. 



-Section of carpel showing tip of carpellary leaf folded to enclose 

 the nucellus. 



-Section of carpel showing cavity closed and integument well 

 developed. Megasporocyte divided. 



—Longitudinal section of carpel showing elongating style and 

 stigma and the micropyle. 



-Section of young androecium showing division of archesporium 

 into wall cells and sporogenous cells. 



-Wall cells divided to form parietal tapetum. Outer wall cells 

 beginning to divide. 



-DelaA'ed division in one primary wall cell. Sporogenous cell 

 dividing to form axial tapetum. 



-Central section showing tapetum fully developed and a splitting 

 between the peripheral tapetum and the sporogenous tissue. 



-Section near tip of stamen showing binucleate tapetuin and 

 spindle. 



-Longitudinal section of more mature stamen showing the same- 



-Microsporocyte dividing. 



-Tetrads. 



-Disintegrating microspore and two celled pollen grain. 



-Mature pollen grains showing tube and two sperm nuclei. 



-Nucellus and archesporial cell. 



-Double archesporium. 



-Megaspores. 



-Nucellus showing megaspores and division in epidermal layer. 



-Two-celled embryo sac. 



—Four celled embryo sac. 



-Eight celled embryo sac. 



-Eight celled embryo sac showing synergidae and oosphere, con- 

 jugating polar nuclei and antipodals. 



—Seven celled embryo sac showing egg apparatus, definitive 

 nucleus and antipodals. Embryo sac enlarging in antipodal 

 region. 



