- 1898] THE LIFE HISTORY OF EUPHORBIA COROLLATA 425 
Figs. 16, 17. Abnormal staminate flowers; one with accessory anthers 
developed at the notch (fg. 76), the other with a cup-like perianth in the 
" same situation (fig. 77). 
PLATE XXIII. 
Figs. 18-20. Young megasporangia, showing first division of primary 
_ archesporial cell into tapetal and primary sporogenous cells, In fig. zo the 
_ primary tapetal has in turn divided, as has also the adjacent epidermal cell. 
_ Fig.21. Next stage in mother cell row. 
Figs, 22-24. One-celled embryo sac with remnant of mother cell row 
_ above and marked development of nucellar tissue in this region. 
_ Fig. 25. Two-celled embryo sac; nucellus dividing further, and epi- 
_ dermis forming two layers of cells. 
Fig. 26. Four-celled embryo sac; several glandular hairs with their con- 
_ Spicuous nuclei applying themselves to “neck ;” differentiation of axial row 
Fé of cells into so-called “channel cells ;”’ portions of the two integuments shown 
‘in outline, 
Fig. 27. Eight-celled embryo sac; the elongated synergids with the egg 
_ between their free tips lie in the upper part of the narrow sac; the polar 
_-fuclei fusing ; the ephemeral antipodals. 
_ Fig. 28. Polar nuclei fusing in transverse axis. 
__ Fig. 29. The upper end of the sac in the eight-celled stage showing the 
pete positions of the synergids, the egg, and the endosperm nucleus to the 
_ “channel.” 
) _ Fic. 30. Fertilization stage; pollen tube with male gamete passing 
tween the disintegrating synergids toward egg lying beneath; the endo- 
perm nucleus has not divided. 
a PLATE XXIV. 
_ Fic. 304, Young microsporangium showing one cell of archesporial plate 
differentiated, 
“Aig, 
31. More advanced stage. 
: Fig. 32, Microsporangium showing two of the four plates of archesporial 
7 one undergoing division. 
Fig, 33. Still later stage, where the hypodermal layer seen at the right 
32 has divided, thrusting the layer under it down toward the center of 
anther ; Only one cell in each of the conelike masses gives evidence of 
ns ing the ancestor of the spore mother cells. 
MiG. 34. A stage in which the tapetum is differentiated ; about twelve : 
_ 8£Nous cells, ten of which show in the section. 
Fig, 35. Later stage; tapetum not yet differentiated. 
