2 1 o Woodworth — The Apical Cell of Fucus. 
Reinke found in Sargassum, Cystoseira , Cystophora , Cysto- 
phyllum and Halydris , one large pyramidal apical cell, from 
which are derived all the tissues of the plant. Reinke’s figures 
7 and 8 show the apical cell of Cystoseira and Halydris. 
Valliante found but one cell for Cystoseira , and. on plate 5, 
figure 2, figures the apical cell of C. barbata as a large wedge- 
shaped cell, triangular in cross section, at the bottom of the 
terminal depression. 
Kny found one initial cell for Pelvetia canalicidata , a close 
ally of Fucus. He describes the apical cell as being pro- 
minent by its large size, with a broad base and the smaller 
end directed upwards. In cross section it appears either 
triangular, quadrilateral, or even square, varying in different 
cases. Segments are capable of further division and are cut 
off from the sides and base of the cell, giving rise to all the 
tissues. In Fucus vesiculosus he could not exactly determine 
the existence of a single apical cell, there appearing at times 
to be several in a row. 
Thus a number of different members of this group are 
known to have but a single initial cell ; and, should we accept 
the conclusions of Reinke and Rostafinski, then Fucus must 
depart widely from its allied forms. I am warranted in my 
belief that the structure of the growing-point of Fucus is 
essentially the same as in the other forms of the group, by 
the facts arrived at in my observations. 
The initial cell of Fucus , as found by me, is a four-sided 
wedge-shaped cell with convex sides, the smaller, upper end 
being rounded and the base truncated, its greater diameter 
being at right angles to the broad surface of the frond. 
Cambridge, Mass., U.S.A. 
