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, calcined 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 

 following 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 calcined, 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 Halicorync, 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 the stalk. 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 



