228 
APOSPORY IN FERNS. 
springing, as they do, from the extreme tips of the pinnae. So 
far, although antheridia and archegonia have been observed on 
these prothalli, and their true nature is thus beyond a question, 
the process of reproduction has not been completed ; plants have 
not resulted. The case, however, constitutes not merely a 
second one of Apospory, but also a new form of the phenomenon. 
To Prof. Bower I am indebted for illustrations of the life 
cycles, normal and abnormal, of the Filices, including the two 
forms of Apospory {vide Plate VI.), of which illustrations I give 
an enlarged view upon the diagram before you. The normal cycle 
{Fig. 3) consists, as already stated, firstly, of the spore-bearing 
fei*n or sporophore, then the sporangium, spore, prothallus, the 
sexual organs thereon, and finally the reproduction of the 
sporophore. This normal cycle is, however, both lengthened 
and shortened by abnormal methods of reproduction ; thus it 
may be lengthened by the parent fern producing young plants 
by adventitious budding on the upper surface of the frond, a 
faculty which the prothallus occasionally also possesses, viz., of 
producing other prothalli by vegetative reproduction, the one 
spore thus yielding numerous plants of the sporophore genera- 
tion {vide Fig. 4, for both phenomena). On the other hand, the 
cycle may be shortened by the prothallus yielding plants of the 
sporophore generation by direct budding without sexual action, 
i. e., Apogamy {Fig. 5), or by Apospory, where, in the case of 
A. F.-f. Clarissima, the spore is missing from the cycle ; the 
stalk of the sporangium producing the prothallus {Fig. 6) ; while 
in the other case of the Polystichum, not merely the spore but 
the sporangium also is excised, the prothallus springing directly 
from the frond of the sporophore {Fig. 7). The further illustra- 
tion {Fig. 8) relates to one of the fern allies (Isoetes lacustris), 
but is exactly paralleled in the fern family by the buds I have 
.already described as formed in the place of sori, e., on the 
under surface of the frond in the plumose Athyria. 
