1914] - PICKETT—PROTHALLIUM OF CAMPTOSORUS 235 
and 35 show about as regular or symmetrical a formation as has 
been found. 
Another point to be noted is that as the prothallia grow older 
the apical group in- 
creases its activity, with 
the result that instead 
of being in a sinus of 
considerable depth it is 
pushed outward to form 
an almost straight mar- 
gin at that place (fig. 
37). Closely related to 
this phenomenon are the 
Cases of proliferation 
now to be mentioned. 
Prothallia which 
have grown for four or 
five months, and those 
Fic. 39.—Old prothallium that has developed 
two special growing regions; X28 and 160. 
which have been allowed to become quite dry and recover, some- | 
Fic. 40.—S 
to those in 
in Hg. 39, but more fully develo 
and showing rhizoid; x 160. oe 
‘oli ¥ sia 
Proliferations antheridia are forme 
pecial growing point similar 
times continue irregular 
_ growth at one or more points 
on the margin. Fig. 38 
shows a part of the margin 
of a large prothallium with 
renewed growth, after desic- 
cation for several days. Fig. 
39 shows two such regions on 
one prothallium. Fig. 40 
shows an advanced develop- 
ment of such a region that 
has produced a rhizoid and 
might continue growth inde- 
pendent of the original pro- 
thallium. On some such 
d regularly and abundantly. 
The . 
Presence of archegonia has not yet been noted on them. 
