[eae vel te) OU 
Figure 80.—Section of megaspore mother-cell with surrounding 
cells, showing spindle of first reduction-division. Eight chro- 
mosomes were counted in this spindle, four of which are shown 
in the figure. >< 800. 
Figure 81.—Portion of section of megasporangium, showing the 
unusual condition of the four potential megaspores in a row, 
the two upper already being resorbed. Or, judging from the 
very indistinct wall separating the two lower cells and from 
their size, this may be a case where only three megaspores 
were formed, and the lowest has undergone the first division. 
> 800. 

Figure $2.—Portion of section of megasporangium, showing omission 
of formation of wall between the two outer potential megaspores, 
these and the next lower becoming resorbed. >< 800. 
Figure 83.—Portion of section of megasporangium showing young 
embryo-sac with two nuclei; upper potential megaspores and 
part of surrounding tissue becoming resorbed. >< 800. 
Figure 84.--Young embryo-sac with four nuclei; showing also 
remnant of upper potential megaspores. >< 800. 
Figure 85.—Mature embryo-sac, showing synergidae, upper polar 
nucleus, egg, lower polar nucleus, and antipodals. >< 800. 
oD’ 
Figure 86.—The three antipodal cells lying in pouch at base of 
nature embryo-sac. >< 800. 
Figure 87.—Pollen mother-cell, synapsis stage. >< 800. 
Figure 88.—Young pollen-grain in tetrad before the dissolution of 
the tetrad wall. >< 800. 
Figure 89.—Pollen-grain just before formation of generative cell, 
showing enclosed starch grains and beginning of wall thicken- 
Ings. >< S00: 
Figure 90.—Pollen-grain showing spindle preparatory to formation 
of generative cell. >< 800. 
Figure 91.—Cross section through middle of pollen-grain at stage 
shown 1n figure 90. >< 800. 
Figure 92.—-Pollen-grain just after formation of generative cell. 
>< 800. 
Figure 93.— Longitudinal section through almost mature pollen-grain, 
showing tube-nucleus and generative cell just previous to form- 
ation of male cells. >< 400. 
Figure 94.—Longitudinal section of mature pollen-grain showing 
the two male cells still united, and the degenerating tube- 
nucleus. >< 375. 
Figure 95.—Longitudinal section of mature pollen-grain, showing 
characteristic dumbbell shape. >< 175. 
Figure 96, a and b.—Surface and profile views, respectively, of the 
pollen-grain wall thickenings, at mature stage. >< 800. [8 
Figure 97.—Pollen-grains, during the dissolution of the tetrad walls 
and formation of the pollen-grain wall. >< 800. 
