THE UNCOILING FRONDS. 17 
fern. Instead, there appears a peculiar flat, green, heart- 
shaped body, scarcely a quarter of an inch across, known 
as the prothallium. On the underside of this are borne 
two sets of organs and finally by a union of their contents, 
a new fern is produced. It is small wonder that this 
complicated process was so longa puzzle to investigators 
of plants. The knowledge of the subject grew very 
slowly. In 1648 the nature of the sporangia was first 
made out, and in 1669 the spores themselves were dis- 
covered. In 1715 Morrison is said to have raised young 
plants from spores but it was not until 1788 that the 
office of the prothallium was known and more than 
thirty years later before its development was observed. 
Lastly it was not until near the middle of the nineteenth 
century that the functions of the small organs on the 
prothallium were discovered. The time required for a 
fern to come to maturity from the spore is from three to 
seven years. 
As may be imagined, many dan- 
gers threaten the young sporeling, 
and some species have devised vari- 
ous “short-cuts’’ by which to avoid 
the perils that often seem to threaten 
the very existence of their race. 
One of the bladder ferns produces 
spores in abundance and in addition, 
little bulblets grow from the under 
surface of the fronds. The spores 
are scattered far and wide and may 
or may not land in a favourable place for germi- 
nation, but the bulblets drop into the soil beside their 
parents, ready to form new plants. It is interesting to 
know that the first fronds from these bulblets are much 
SORI OF POLY PODIUM. 
