APPENDIX. 
93 
headed projections (antheridia), while upon a thickened cushion, 
close to the indentation of the heart, a little cluster of teat- 
like bodies (archegonia) also appears. At the base of each of 
the latter, and embedded in the substance of the prothallus, 
there lies an embryo seed, a single one, but otherwise constituted 
precisely like the seed in the ovary of a flowering plant. 
Within the bullet-headed bodies lie closely packed a number of 
tadpole-like organisms (antherozoids), which, when mature, burst 
the capsule, and by the aid of cilia or moveable hairs, swim 
actively about in the dew-like moisture which usual y is present 
on the under side of the prothallus. These are equivalent to 
the pollen grains of flowering plants, and perform the same 
office by making their way to the archegonia, or teat-like 
projections, and fertilising the embryo seeds at their bases. We 
thus see that the Fern practically bears its flowers on the tiny 
heart-shaped prothallus, but on such a minute scale that it is 
small wonder that the process eluded the research of botanists 
until the above date. The seed once fertilised sends down a 
root proper into the soil, and a frond proper into the air through 
the indentation of the heart, the prothallus itself then usually 
perishing. As a rule only one seed yields a plant, the rest 
of the cluster aborting. If, however, the prothallus be cut in 
two with a razor through the cushion, each half is capable of 
developing independently, and, indeed, experiment has shown 
that by repeated division a considerable number of Ferns may 
be produced from a single spore. A glance at our illustrations 
will make the normal process perfectly clear, since every stage 
is shown ; but Nature sometimes varies it, and since Suminski’s 
discovery of the archegonia and method of fertilisation, which 
completed this normal life cycle, it has been found that Nature 
has “rung the changes,” so to speak, in every conceivable 
fashion, cutting out of the life-cycle, in one way or another, 
every one of the stages without exception. In the first place, 
Professor Farlow in 1874 found that the prothalli in some Ferns, 
instead of producing archegonia, or the teat-like bodies aforesaid, 
with seeds at their base, developed simple vegetative buds or 
bulbils in their place, and so produced the spore-bearing Fern 
direct without any sexual agency at all (apogamy). This 
eliminated both (antheridia with their contained antherozoids) 
and archegonia from the life cycle. This was followed in 1884 
by the writer’s discovery of apospory, in which the spore itself 
is eliminated, the prothallus being produced by direct out-growth 
from the frond, and then running the normal course. This 
was eventually found in six species and twelve cases, viz., 
Athyrium Filix-foemina (3), Polystichum angulare (4), Lastrea 
pseudo-mas (2), Scolopendrium vulgare (1), Pteris aquilina (1), 
