328 BOTANICAL GAZETTE [may 
the apex. Some idea of the relative length of time during which 
this state of things continues may be gained by comparing the 
integuments of figs. 7 and § with zo and 77. 
The subsequent divisions in the elongated sporogenous cell 
take place in quick succession. I have obtained a very large 
number of karyokinetic figures of these divisions, for since 
Eichhornia is peculiar in having all the flowers of a spike in 
pretty nearly the same stage of advancement, a single spike may 
yield upwards of two thousand ovules all of nearly the same age 
The first spindle is in the apex of the cell and the division is 
very unequal (fig. 72). There is no uniformity in the order in 
which the succeeding divisions occur. Sometimes the upper 
cell divides first, sometimes the lower; more rarely, as in fig. 
73, they divide simultaneously. The spindle in the upper cell 
is almost always obliquely placed (it may even be transverse), 
and it is doubtful if cell division is ever completed or even ® 
cell plate formed. The division in the lower cell is also unequal, 
so that the lowest cell of the four, the fertile mother cell, 1s 
from the very first quite as large as the three sterile ones 
together (fig. 73). From a study of a large number of a 
similar to figs. rg and 15, I have been led to believe scant 
four mother cells when formed in this way are seldom, if ever, 
separated by walls. = 
All shades of transition between the two lines of eT i 
development described above may easily be found wee 
the same flower. Thus figs. 77, 12, 73; 76,17 and rate a ‘sion 
the same ovary. “ig. 77 shows a case in which the first heal 
of the primary sporogenous cell has taken place when it pe 
half grown. In fig. 76 it will be seen that after the oe # age 
only the lower cell has lengthened and divided, and, the 3 by 
division of the.upper cell has begun, this has been stoppe? *- 
the encroachment of the two cells below. the tapetal 
The three sterile mother cells, and after them . capidly 
the nucellus, 
e, which soon sg 0 
cells and other cells in the apex of 
absorbed by the growing megaspor 
abut directly against the epidermis. 
oe ee eee eae ered pe oe ae PT eed 
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