654 Lewis . — The Life History of Griffithsia Bornetiana. 
when, as is often the case, Griffithsia is attached to other algae of cylindrical 
habit the disk is replaced by a tangled mass of rhizoids, which are short, 
thick-walled, and filled with starch. Inspection of a number of specimens 
shows all stages of transition from a mass of rhizoids to a well-developed 
attaching disk. The disk may be said to be formed of rhizoids in contact 
laterally. The development of the attaching organ is described on page 676. 
The attaching disk, when present, is formed of a single layer of heavy- 
walled cells, bright pink in colour owing to the presence of numerous 
chromatophores, densely filled with protoplasm, and packed with large 
starch grains (Figs. 51, 52). From it new shoots may arise. 
Judging from analogy with other forms (see Oltmanns, 59 , i, p. 648 ; 
and ii, p. 212) we may assume that the plant winters over by means of the 
attaching disks or the mass of rhizoids at its base. In the spring these give 
rise to the plants which reach perfection in the summer. The evidence for 
this is rather negative: 1. The first plants found in 1907 possessed the 
attaching disk already well developed, whereas we know that in the sporelings 
the basal disk is developed quite slowly. 2. From the time Griffithsia was 
first found in July development was extremely rapid, and this seems to 
point to the conclusion that the plants drew on some reserve food-supply. 
Sexual Reproduction. 
The antheridia are distributed as caps over the upper ends of the 
somewhat globose terminal cells of the male plants (Fig. 2). They are 
formed as the terminal cells of short, much branched antheridial filaments. 
On a cell of average size there were found to be about 500 of these 
filaments, each of which produce about 50-75 antheridia, a total of 
25,000-37,500 antheridia for each fertile cell of the male plant. The number 
of antheridia on a single antheridial filament, as well as the number of 
filaments produced on a single cell, varies greatly. 
The mode of origin of the antheridial filaments is as follows : While the 
terminal cell of the male plant is still small and not much swollen (measur- 
ing on an average 0-2 mm. long and o-i 5 mm. broad at this stage) about 
100-200 protuberances arise simultaneously on its apical surface (Fig. 53). 
Each protuberance is at first hemispherical. There is in each a single 
nucleus, surrounded by dense, clear cytoplasm, which is in free communica- 
tion with that of the mother-cell (Fig. 54). Their formation is not con- 
nected with nuclear division, but takes place while the nuclei are in the 
resting condition. The withdrawal of so many nuclei from the upper 
portion of the parent-cell leaves this region almost free of nuclei. As 
growth proceeds, however, nuclei wander up from the basal region, and 
become again evenly distributed in the cytoplasm. 
Each primary protuberance is soon cut off from the mother-cell by a 
delicate partition, which is laid down by the protoplasm in the same way as 
