86: BOTANICAL GAZETTE [FEBRUARY 
Fig. 5. Microsporangium of 2. multifidus, showing a definite relation od 
tapetal cells to the wall layers, and a differentiation of the endothecium 
Leitz oc. 4, obj. 7a. 
Fig. 6. Microsporangium of &. septentrionalis. 
Figs. 7-11. Development of microspore tetrad in 2. septentrionalss, 
Fig. 12. Second nuclear division in pollen mother cell, occurring in same 
plane, and showing free nucleoli and kinoplasmic threads. Zeiss oc. if 
obj. 2™™. . 
Fig. 13. First nuclear division in pollen mother cell of 2&. multifidus, 
showing free nucleoli and polar radiations. Leitz oc. 4, obj. jy. 
Fig. 14. First nuclear division in pollen mother cell of 2. multifidi 
showing “centrospheres.” 
FIG. 15. Microspores of R. septentrionalis, showing thin areas in tit 
exospore. Leitz oc. 4, obj. 7a. | 
Figs. 16, 17. Mature microspores of R. septentriona/is, showing the t¥ : 
nuclei, 
Figs.’ 18-20, Macrosporangium of R&. septentrionalis, with single archt 
sporial cell; in fig. 20 a periclinal division is represented in the overlyil§ 
epidermal cell. 
Fig. 21. The same, showing subjacent row of cells in the sporangiua 
Sometimes mistaken for a row of mother cells. 
Fig, 22. The same, showing enlargement and first nuclear division. 
Fic. 23. The same, showing the first division completed. 
Figs. 24, 25. Archesporium of 2. septentrionalis, composed of mort 
than one cell. a 
PLATE V. d 
FIG. 26. Macrosporangium of R. septentrionalis, with eight-celled ar 
sporium, we 
FiG. 27. The same, with three archesporial cells in an advanced sit 
of development, the two to the right in the “two-celled”’ and “ four-cé - 
Stages of the embryo sac. Zeiss oc. 4, 0b}, 2™. a 
Fic. 28, Macrosporangium of R. multifidus, with the remains of a secol 
archesporial cell. ee 
FIGs. 29-31. The same, showing successive stages in the developm 
of the row of four mother cells. a 
¢ the fer 
. ot 32. The same, showing the beginning of the enlargement of ee 
mother cell, and the destruction of the adjacent cell. 
celled arch 
laps 33. Macrosporangium of R. abortivus, showing a two- 
Sporium. 
