PHHOPHYCEA 73 
the apex. The apical cell persists throughout life at 
the ends of the main shoot and branches. 
The Reproductive Organs. — Conceptacles are 
formed by the transformation of one of the young 
epidermal cells near the apex into an initial cell 
resembling in all essential points the pear-shaped 
apical cell. This initial cell is the homologue of the 
initial cell in the development of the conceptacles of 
the Fucacece, but it undergoes no division and no fur- 
ther development. The epidermal cells surrounding 
it divide and the cortical cells in its neighbourhood 
increase in size; by a combination of these processes 
the initial cell is placed at the bottom ofa cylindrical 
depression, while hairs (paraphyses) arise from the 
youngest epidermal cells with others formed earlier 
surrounding the mouth. The upper pear-shaped 
portion of the initial cell stands out prominently 
from the base. In Fucus, on the other hand, a 
young conceptacle with a small ostiole is formed 
before the paraphyses appear. The conceptacle 
enlarges by radial division of the lining cells, and 
though the base becomes larger than the mouth, the 
flask-shaped form seen in the Fucacece does not 
occur. The paraphyses are long, septate, and 
unbranched, dividing at the base, and forming tufts 
which emerge far beyond the mouth. The con- 
ceptacles at this stage thus resemble in appearance 
the cryptostomata of the Pucacew. 
The sporangia, which are unilocular, are formed 
among these paraphyses as protuberances of the 
lining cells of the conceptacle. They elongate and 
enlarge into club-shaped bodies with the base sunk 
