PICKETT: EMBRYO-SAC OF ARISAEMA TRIPHYLLUM 235 
G. 6. Longitudinal section of ovule showing one megaspore mother cell and 
completed periclinal division of epidermal cells. 225. 
Fr Cross section of nucellus showing layer of 2 to 3 cells surrounding three 
megaspore mother cells. 335. 
Fic. 8. Longitudinal section of the whole ovule and part of ovary walls. 225. 
Fic. 9. Cross section of nucellus similar to ric. 7, but showing different ar- 
rangement of megaspore mother cells. This shows very nearly simultaneous 
preparation for nuclear division. an 335. 
Fic. 10. Cross section of nucellus showing the spindle of a longitudinal first 
division of a megaspore mother cell. 335. 
Fic. 11. Longitudinal section of nucellus with four megaspore mother cells. 
The position of the two at the left suggests a possible origin from a common arche- 
sporial cell. 225; 
FIG. 1 Longitudinal section of ovule to show the development of the integu- 
ments at the time of preparation for first tetrad division. 125. 
Fic. 13. Cross section of nucellus to show irregularity of periclinal division of 
outer cells. 335. 
Fic. 1 Longitudinal section of ovule to show the development of integuments 
at the time of the first tetrad division. 125. (See FIG. I 
Fic. 15. Longitudinal section of nucellus showing some sporogenous cells 
Sraieee by the growth of others. X250. 
Fic. 15a. Sporogenous cells of FIG. 15. 30. 
iG. 16. Higher magnification of the nucellus shown in FIG. 14. 250. 
IG. 17. Longitudinal section of nucellus showing a possible tapetal cell, ¢. 
I itudinal secti f llus.showing a row of four potential mega- 
1G. 1 aaa section of nucellus showing two megaspore mother cells, 
one below the other. 50. 
Fic. 19a. Sporogenous cells of FIG. 19. 830. The nuclei are in synapsis. 
and the wall formed after the first division. This shows the sporogenous cells buri 
unusually dee 50 
IG. 23. ‘ubekaues 22 
Fic. 24. A later stage than in ip se x 250. 
Fic. 25. Section of a the first nuclear division. 830. 
Fic. 26. Section showing fous nuclear stage in the development of the embryo- 
1 c W wall £ e FG REM ee Nan Bes ot 250. 
