384 | WoopBuRN: DEVELOPMENT OF THE EMBRYO SAC 
BIBLIOGRAPHY 
Coker, W. C. The development of the seed in the Pontederiaceae. 
Bot. Gaz. 44: 293-301. 1907. ; 
Coulter, J. M. Contribution to the life-history of Ranunculus. Bot. 
Gaz. 25: 73-86. 1898. 
Johnson, D. S. On the development of certain Piperaceae. Bot. 
Gaz. 34: 321-340. 1902. 
Juel, H. O. Parthenogenesis bei Antennaria alpina. Bot. Centralbl. 
74: 369-372. 1898. 
Overton, J. B. Parthenogenesis in Thalictrum purpurascens. Bot. 
Gaz. 33: 363-375. 1902. 
Smith, R. W. A contribution to the life-history of the Pontederiaceae. 
Bot. Gaz. 25: 324-337. 1808. 
Smith, R. W. Endosperm of Pontederiaceae. Bot. Gaz. 45: 338-339. 
1908, 
Explanation of plate 16 
Fic, 1. A two-nucleated embryo sac, upper part of nucellus disorganizing. 
Fic. 2. Egg apparatus and polar nuclei. One or two antipodal cells were 
present in the next section. 450. 
Fic. 3. Embryo sac sicwine antipodals. Upper part of nucellus has disap- 
peared. 
Fic. 4. Reg apparatus. Polar nuclei flattened on contiguous sides. XX 525. 
Fic. 5, 6, and 7 are successive sections of the same ovule. X 50. 
Fic. 6 and 7 represent only the micropylar region. 
Fics. 8 and 9 are successive sections through corresponding regions of an older 
embryo sac, showing two distinct groups of cells. 150. 
Fic. 10. ction of embryo sac showing peripheral endosperm nuclei and a 
group al disorganizing cells, evidently the egg apparatus. x 55- 
Fic. 11. Showing the development of the endosperm in two regions. XX 55. 
Fic. 12. Endosperm completely filling the embryo sac 
Fic. 13. Outline sketch showing extent of nucellus ib eicided by inner integ- 
ument, before formation of megaspore 
