PREFACE. 
xviii 
fixedness to the plant. It is obvious that the produc- 
tion of young plants (in-place of spores) which do not 
fall off the fronds or lose the protecting wing of the 
parent until strong enough to provide for themselves, has 
an important connexion with the perpetuation of the 
Fig. 13. Fig. 13a. 
species. There have been cases among our native ferns in 
which the production of bulbils has become the only means 
for the increase of the species, all parts of the frond yielding 
them. I am indebted to Mr. Clapham, of Ramsdale Bank, 
Scarborough, for remarkable illustrations of such abnor- 
mities, which I could not better describe than in his own 
words. “ Scolopendrium Wardii,” he states, “ a seedling 
raised in Glave’s Garden, is one of the most singular of our 
native varieties. In a warm moist temperature, especially 
if covered with glass, it becomes astonishingly viviparous, 
the veins occasionally carrying tiny plants, while each 
projection of the margin of the frond possesses one. I have 
counted sixteen bulbils on one part of a frond. These, 
when cultivated, yield a proportion of plants bearing sori, 
although the majority resemble the parent in its bulbiferous 
character. Some years ago I had a plant of Adiantum 
Capillus Yeneris, several fronds of which, instead of unfolding 
their pinnules, became branches of bulbillse. I noticed a 
similar change in an Adiantum which I gathered in the Isle 
of Man, in 1864.’' 
The Position of the sori upon the frond presents occasional 
anomalies which, were the history of certain varieties un- 
