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Charles E. Allen 
at any earlier stage between two successive mitoses ; at least, the impression 
gained from an examination of sections of antheridia of different ages 
is that on the average the androcyte mother cells are larger than the cells 
belonging to some of the immediately preceding generations, instead of 
smaller, as would be the case had their growth been proportional to that 
of the androgones (compare Figs. 66 — 86, PI. VIII, with Figs. 38 — 40, 55, 
PI. VII, and Fig. 65, PI. VIII). There is, of conrse, as the figures show, 
considerable Variation in size between cells of the same generation at 
substantially the same period of development, and the average difference 
between the cells of the respective generations in qnestion is not sufficient 
to make a comparison of individual cells of much value; but the general 
impression just stated is that wliich is given by sections containing hundreds 
of cells. 
The androcyte mother cells are also distiuguished from the androgones 
by the relatively diffuse staining of their cytoplasm ; an appearance which 
may result from the considerable growth that these cells seem to have 
undergone, accompanied by an increase in the proportional amount of 
cell sap. 
Another distinguishing feature of the generation now in question 
is the gradually increasing thickness of the cell walls, a change which seems 
to indicate the beginning of the process of dissolution of the walls 
that is to reach its conclusion after the division of the mother cells and 
while the androcytes are beginning to develop into antherozoids. The 
greater thickness of the walls is first apparent at corners where three or 
four cells join (PI. VIII, Fig. 66); the result is a rounding at such corners 
of the outline of the individual cell. The thickening of the walls and 
rounding of the corners as yet differ only in degree from the conditions 
found in earlier cell generations (Figs. 63, 64); and there is some difference 
between the mother cells in various antheridia with respect to the time 
when the thickening and rounding begin to be noticeable. Thus, Figure 67 
represents an androcyte mother cell apparently at about the same stage 
of development as that of Figure 66; the walls of the former, however, 
are not noticeably thicker than those of the androgones shown in Figures 63 
and 64. But at whatever moment the process of thickening begins, it 
continues during the preparations for the division of the androcyte mother 
cells and during the division itself, so that the thick walls finally constitute 
a very noticeable feature of the preparations in which these later stages 
appear (PI. VIII, Figs. 70, 76, 77, 81; PI. IX, Figs. 98, 99, 121, 123, 124). 
The progressive change in the nature of the cell walls, which I have 
interpreted as the beginning of their dissolution, is evidenced only by their 
