DEVELOPMENT OF COXCEPTACLE IN THE FUCACEyE, 47 
ridia appears an alteration in the system of branching from 
inonopodial to sympodial_, as will be seen from fig. 12. 
Each of the lower lateral axes is terminated by an anthe- 
ridium (1) which is cut off* by a transverse cell-wall. This 
stops further growth in that direction. As before shown in 
the case of Fucus, below this cell-wall appears a lateral 
branch, which is in its turn again terminated by an anthe- 
ridium (2), and so on. The system of branching is thus 
rendered sympodial by the formation of antheridia ; the 
apparent axis being a pseudo-axis, composed of a series of 
pedicels of successive antheridia. As to the arrangement of 
the successive antheridial cells, the same remarks will apply 
here as were made upon the antheridia of Fucus serrahis. 
As in Fucus, the antheridia are not only formed on the 
lower branches of primary hairs ; unicellular papillae are 
here also formed by outgrow’th of single cells of the lining 
tissue ; these develop as described in the case of Fucus 
serratus (cf. fig. 8, i, ii, iii). 
General remarks. 
In drawfing our conclusions from the facts before us, the 
most striking point is that, in all cases described, the forma- 
tion of the conceptacle is preceded hy the decay of one or more 
cells lohich occupy a central position with regard to the 
changes which folloio. The number of the ceils thus re- 
moved is various, and the manner of their destruction is not 
constant ; but the fact remains in all cases. I must own 
inability to suggest a parallel to this.^ 
A point which is not so obvious, but 'which appears of 
similar constancy, is that the cell or cells tchich decay are in 
all cases members of a linear series. It depends upon the 
activity of division, in a direction tangential to the surface 
of the thallus, how this series is characterised ; -whether, as 
in Fucus, w'here the division is slow, and even ceases, the 
apical cell of the series hangs behind the surrounding tissue; 
or whether, as in Himanthalia, where the division is often 
repeated, the series is elongated, and, protruding beyond the 
surface of the thallus, is called a hair. The small import- 
ance of this difference is shown by the variety -which exists 
in this respect in specimens of the same species, under dif- 
‘ Reinke (‘ Eut\A\ Unters ; iiber die Dictyotaceeii,’ 1878, p. 47) speakiug 
of the hairs, whicli he termed “ Sprossfadeii,” remarks that they arc always 
unbranched ; they are grouped in slieaves or rows, and grow, at least later, 
exclusively by division of their basal cells; they form the precursors of the 
reproductive cells, and fall off when these appear. How far these may be 
compared with the initial cell or hair of the Fucaceai it remains for closer 
observation to decide. 
