The Classification of the Aigce. 121 



it of the spermatozoid {z) from the " dwarf -man " (/»). Pring- 

 sheim, Morphologie der Oedogonieen. 



The fructification of the Fucacese was several years ago 

 studied out and illustrated by the lamented Thuret, and is, per- 

 haps, of all the Melanosperms best known, as it is the most 

 easily observed. Plate XL, Fig. 3, represents a section through 

 the conceptacle of Fucjis platy carpus, after Thuret. At c, we 

 observe the cortical layer of the frond which is seen to be con- 

 tinued quite around the interior surface of the conceptacle. 

 The colorless hairs (//) which line the interior of the concep- 

 tacle extend out through the mouth and form minute tufts, 

 visible to the naked eye, upon the surface of the frond. The 

 oogonia (<?) are seen plentifully scattered over the interior of 

 the conceptacle. At first they grow up large, ovate, 

 densely-filled cells. The cell-contents are soon seen to be divided, 

 and in the Fucus there are formed in each oogonium eight oos- 

 pores. In other genera the cell-contents remain undivided, and 

 one large oospore is formed, as in Pycnophycus, Himanthalia, Cys- 

 ioseira, Halidrys. In others it parts into two Felvitia, and again 

 in others, as Ozothalia vulgaris, into four. 



The antheridia are formed in the extremities of the branched 

 hairs which grow from the surface of the conceptacle. They 

 are, indeed, the slightly swollen branches of the hairs, not 

 shown in Plate XI., Fig. 3, but seen highly magnified at Fig. 4, a, 

 which are filled at first with a granulous protoplasm, which, 

 in the end, changes into great numbers of minute spermato- 

 zoids, each armed with two or more cilia, and marked laterally 

 by a noticeable red point (Fig. 4, h, X ZZ^)- 



Fructification takes place outside of the conceptacle. The 

 oogonium parts with its eight oospores, and they come forth 

 from the conceptacle still enclosed in an inner sac of the 

 oogonium. Fig. 4, 0, shows an oogonium of F. vesiculosus with 

 the cell-contents divided into eight parts. At c, the process has 

 continued, and the oospores fully rounded out and ripened. 

 They are also stripped of the outer cell-wall of the oogonium. 

 At this stage and in this condition, they come forth from the 

 conceptacle and gather about the mouth on the surface of the 

 frond. The antheridia also detach themselves from the hairs 

 on which they grow, and pushing out collect in little heaps 

 about the opening of the conceptacle. This all happens at low 

 tide while the plant is lying out of the water in the moist air. 



