148 SEAWEEDS 
ally irregular protuberances at the tip. The plant 
dies down, and the lower part of the stalk, closed 
with a membrane at the base, remains alive during 
the winter, and may be described as consisting of 
two portions, viz. the foot, calcified and irregularly 
branched, and a basal, rhizoid body. This basal 
body increases with age, and acts as a storehouse 
of reserve-material for further growth. In the 
follewing year a cap without spores is produced, 
while the stalk, before this happens, gives rise to one 
or more whorls of branched hairs. These hairs are 
not calcified, and are soon thrown off, leaving only 
rings of scars on the stalk of the cap-bearing plant. 
After giving rise to several sterile plants in succes- 
sion, eventually a fertile cap is borne. 
This production of whorls of hairs is interesting, 
not only in throwing light on the homology of the 
sporangial rays, but in relation to the neighbouring 
genus Halicoryne, which possesses alternate whorls 
of fertile and sterile branches. The sterile whorls 
consist of repeatedly multisect hair-tufts developed 
in groups of eight; but they soon fall off, and leave 
round scars on thestalk. Between these on the full- 
grown plant there are sixteen-branched whorls of a 
different kind—the sporangial rays, which are com- 
pletely free. Each ray is furnished on its upper sur- 
face near the base with a small protuberance bearing 
one or two diminutive rudimentary hairs, recalling 
the corona superior. Interesting also in this con- 
nection is the fact that Acetabularia crenulata, in the 
normal course of its development, and not as a 
monstrosity, produces several caps in succession 
