234 BOTANICAL GAZETTE [MARCH 
varied as to both time and position. In long, protonema-like struc- 
tures the beginning of a specialized growth region is usually indi- 
cated by the division of a cell once or twice removed from the distal 
end (fig. 1). In case a plate of cells has been formed as mentioned 
above, a group of cells anywhere about the periphery of this plate 
may become more active than the neighboring cells, and thus con- 
stitute an apical region or 
group. The formation of 
a distinct, individual, 
yo V-shaped apical cell has not 
been noted, although forms 
like figs. 8, 29, 30, and 32 
suggest such. In the plant 
shown in fig. 8 the growing 
region would probably 
appear between a and 
rather than as a result of 
any activity of the cell at 
In many instances the 
apical region is quite sym- 
metrically placed (fig. 14); 
but an examination of figs. 7, 12, and 17 will show the extreme 
variation of position, and how far from symmetrical the placing of an 
apical group may be. Fig. 19 shows an even more interesting Case, 
of which a few have been found, where two such regions have been 
Fic. 37.—Large prothallium with distal 
margin almost plane as a result of activity of 
large apical group; X28 and 160. 
Fic. 38.—Portion of margin of large prothallium, showing almost continuous 
growing group; X160. 
formed. The very striking irregularity in the formation of the 
apical group is further shown in figs. 28-36 and in figs. 56 and 57: 
Fig. 28 with the group (a) entirely lateral to the evident axis of 
elongation, fig. 36 (an enlargement of a in fig. 18), and fig. 34 with 
the apical group beside a sinus are worthy of notice. Figs. 33, 34 
