1898 | THE LIFE-HISTORY OF RANUNCULUS 79 
sporial cell of Ranunculus is but the remnant of an archesporial 
mass of cells, which still appears in various stages of steriliza- 
tion. In some cases two or three cells of a several-celled arche- 
sporium were observed to develop to mature size, but usually 
not more than one was observed to divide. In certain prepara- 
tions, however, development of several of the archesporial cells 
was observed to have proceeded further ( fig. 27), some develop- 
ing to the “‘two-celled”’ and ‘‘four-celled”’ condition of the embryo 
sac. In the case of R. septentrionalis, on account of imperfect 
material, only a single stage of development was noted, but as 
a complete series was obtained from R. multifidus, it seems 
probable that the same division into four mother cells occurs. 
In no case was a primary wall cell (tapetal cell) cut off, the 
archesporial cell dividing directly into mother cells. 
In R. multifidus the sequence of events from archesporium to 
macrospore was obtained in detail. Indication of an occasional 
two or three-celled archesporium was also observed (jig. 28). 
The series of changes from the archesporial cell to the axial row 
of four mother cells is represented in figs. 29-32, and in every 
case observed the lowest cell of the series developed the macro- 
spore. 
In R. abortivus the same stages were observed. fig. 33 rep- 
eee a notably well-developed archesporium of two cells, 
while figs, 34 and 35 indicate the same steps in the development 
of the macrospore as those observed in R. multifidus. In the 
last two figures the condition of the integuments indicates the 
Stage a the ovule in which the sporogenous development occurs. 
In its earliest condition, after distinct differentiation, the 
mactospore of R. septentrionalis is almost globular ( fig. 36), with 
Prominent nucleus and nucleolus. Soon it begins to elongate 
In the direction of the long axis of the nucellus, with enlarge- 
my : the nucleus and characteristic ante-division nuclear 
mae = SHE: 37). Insome cases the macrospore becomes so 
divisions ee as to be cylindrical. The series of iaanees 
ich occur in the macrospore is indicated in jigs. 
