Woodworth . — The Apical Cell of Fucus . 205 
was imbedded in paraffin and sectioned in ribbons on a Jung 
microtome, then mounted in balsam. By the ribbon method 
of sectioning every section was preserved, and in its proper 
order, a most desirable thing for the object in view. 
Fucus FURCATUS, AG. 
Fucus furcatus is one of the commonest of the Fucaceae 
found on the New England coast north of Cape Cod ; it 
occurs from Massachusetts Bay to Greenland. The material 
that I studied was collected at Nahant, in the month of 
February. The ultimate divisions of the frond of F. furcatus 
are more narrow than in other related species, and the midrib 
is much more prominent. It is characterized by the absence 
of vesicles or air-bladders, the great length of the receptacles, 
and the very regular dichotomous branching. It is found in 
the water at about low-water-mark, and does not occur so 
high up as F. vesiculosus. 
The ends or tips of the divisions of the frond may be of two 
kinds. First the tips may be truncated or flattened with a 
depression in the centre, the depression being elongated or 
slit-like, the long axis of the slit being parallel to the broad 
surface of the frond. In other cases this terminal depression 
may be wanting, and in such cases the tip is conical and 
tapers off to a point. In the present connection I shall 
consider only such tips as have the depression, for the 
characteristic features to be described in this paper were 
found upon such. 
If we section a tip of F. furcatus longitudinally, in a plane 
at right angles to the terminal depression, we get a state 
of things as shown in Fig. 1. At the bottom of the pit, 
which here appears as a cleft, is a large cell, appearing 
triangular in section, with slightly convex sides and the more 
acute angle directed upwards, Fig. 1, A. Immediately adjoin- 
ing the large cell (in this case to the left) is another cell, 
smaller in diameter than the first, but equal to it in height, A'. 
A similar cell, but smaller still, is seen to the right, A " . 
Adjoining the two last-named cells there are on either side 
Q % 
