54 ALTERNATING GENERATIONS 
Funaria, Brizi),1 and from various species of Ferns belonging to the 
Hymenophyllaceae and Polypodiaceae,? but no examples are on record 
from the Lycopodiales or Equisetales. Those cells which would in the 
normal course produce the spores take no part in the formation of the 
gametophytic growths. In Anthoceros the origin of these is commonly 
from sub-epidermal cells: in the Mosses from the cells of the seta, or of 
the sporogonial wall; while in Ferns the archesporial cell if already defined 
in a sporangium is abortive. Thus the aposporous growths are in no 
sense mere irregularities of 
development from sporogenous 
cells. In Anthoceros each 
growth is apparently referable 
in origin to a single cell, and 
the same is probably the case 
also for Mosses. But in the 
Ferns this is not so: here the 
vegetative development may 
start from a sporangium formed 
in its normal place: a plurality 
of the cells of the stalk, or 
of the sporangial wall surround- 
ing the abortive central cell 
may divide, and assume pro- 
thalloid characters (Fig. 37), 
or the growth may arise from 
the receptacle of the sorus 
(Fig. 37E): or again, it may 
be initiated at some point 
on the leaf, usually marginal, 
which thus extends directly 
into the prothallial expansion. 
; ; and may bear antheridia and 
olen ie ene at gun Hales ee toan archegonia (Fig. 37 8B, C, D). 
areneeeuaan: ee a nuclei are present in a single The matter may be further 
complicated by the combination 
of apogamy and apospory in the same individual, and this condition has 
been seen in about half the recorded cases of these abnormalities in Ferns. 
The apogamous seedlings of Wephrodium pseudo-mas, var. cristata (Cropper), 
not only sprang themselves in an apogamous manner from the prothalli, 
but proceeded almost at once to an aposporous production of new prothalli 
on the margins of the young leaves? These prothalli bore antheridia, 
Fic. 36. 
ldnn. Inst. Bot. Rom., v., Pp. 54- 
2For references see Engler and Prantl, Mat. P7., 1. 4, p. 88, and Goebel, //ora, 
1905, Pp. 239. 
3Druery, Journ. Linn. Soc., vol. xxix., p. 479. 
