

18 BRITISH FERNS 
2. That, given a prothallus, the fern might be produced by the 
aid of a sexual bud, formed in the same place on the scale as a. 
sexual one, instead of by the normal interaction between anthero- 
zoids and archegonial seed embryo, and thus eliminate both of 
these (apogamy, previously discovered by Prof. Farlow). 
3. That the prothallus itself was capable of bearing spores, so 
that the frond-forming generation was eliminated, and given the 
power of these spores to perfect and produce offspring of like 
capacity, the frond stage of the fern itself, as we know it, might be 
replaced by a minute Marchantia-like growth of small green scales, 
a reversion, in fact, to one of the primary forms of vegetation. 
This fact was demonstrated by Dr. Lang,! but so far these prothallial 
spores have not germinated. 
4. As regards the elimination of the prothallus, this is evidenced 
by innumerable cases of bud or bulbil reproduction, by which 
young plants are produced by excrescent growths on the fronds 
and elsewhere, such as we see in the familiar Asplenium bulbiferum 
in which the fronds are profusely dotted with young plants. 
То illustrate these various short cuts we reproduce Professor 
F. O. Bower's diagrams in Fig. 8; but it must be borne in mind 
that all these peculiar vagaries have been noted in connection 
with varietal forms of Ferns, that is, such as present marked diver- 
gencies from the ordinary. form of frond, which has led to special 
study of their behaviour in the prothallus stage, with these re- 
markable results. It is therefore seen that the life cycle of a Fern 
is not only more complicated than that of a flowering plant, but 
that it is capable of being varied in so many ways, that every 
individual phase of the normal process may be omitted and repro- 
duction yet be successfully effected. 
Finally, our description of the Life History would be incomplete 
did we omit a reference to the wonderful arrangement by which the 
spores are scattered when ripe. On examining the heaps of spore 
capsules, we shall find them in most species—the exceptions we 
may ignore—to be beautiful oval, shining brown bodies, supported 
on short ribbed stalks, and that these ribs extend right over the top 
of the capsule, like the ridge of a fireman's helmet, only stopping 
half-way down the opposite side (Fig. 2). When the spores are 
ripe, this ribbed portion contracts, and eventually exercises such a 
strain that a crack appears at the point where it ceases ; this slowly 
widens, exposing some of the spores, and after a wider and wider 
yawn, the whole of the top flies back with such violence as to jerk 
the spores in all directions. A tiny pinch of capsules, placed on a 
glass slip and watched under a microscope in а warm room, is а 
1 W. H. Lang, M.B., B.Sc., on * Apogamy and the Development of Sporangia 
upon Fern Prothalli. Phil. Trans. Royal Society, vol. 190 (1898), pp. 187-228. 

