196 THE JOURNAL OF BOTANY 
until it branches into two ee at its summit; in H. Tuna 
the filament resulting from the fusion branches immediately oe 
two, and each of these fone branches seat a . after a tim 
into two sporangiophores. Thus fro m the fusion of two Pisnents 
duced (see figs. 8, "6 8). 
\s regards the sporangia of either species, I am unable to give 
details of their development, or describe the escape of the zoospores 
from personal observation. But MM. Derbés & Solier (i. c. p. 47) 
describe the zoo spores after pees escape as follows :—‘‘ There is 
attached to the posterior part; at other times this latter was 
wanting. In other = — there appeared to be only one at 
the summit of the rostrum, and very often we have not been able 
to see any at all, either in rout or behind. As to the move- 
ments, these zoospores are entirely c omparable with others. We 
have not been able to frei ain silos resting-spores or germinations.”’ 
as I can ascertain, the fruiting season of H. Tuna, the 
the sporangia and the germination of the zoospores. 
In this —_ of the vegetative and reproductive parts of Hali- 
meda, it is seen that all fresh growth is preceded by a fusion of 
filaments of the central strand. The meaning of this fusion is at 
present not quite clear. It may, indeed, be suggested that we have 
fungi, where a fusion of two filaments precedes the formation of 
spores ; but in Halimeda we are met by the difficulty that such a 
fusion is not confined to filaments destined to bear sporangia, but, 
as is mentioned abe is equally characteristic of filaments which 
are purely vegetative. For each filament of the strand which issues 
from the apex or angles of a joint to form a new join e pro 
duct of a — of two or three filaments just within the periphiisy 
of the old jo Inasmuch as these fusions are found to precede 
the rae sap of new joints on the one hand, and of sporangiophores 
on the other, the obvious inference is ‘ that the fusicns provide 
powerful stimulus for further growth, whether vegetative or repro- 
ductive. They form new and vigorous growing points. But what 
Of the material of H. Tuna in fruit, so kindly sent me by Mon 
Bornet, slides showing sporangia hay e been deposited in the British 
Museum ; ; and a herbarium specimen showing the marginal fringe 
of fruiting filaments has been mounted in the Herbarium of the 
Royal Gardens, Kew. I am much indebted to my husband for 
criticism and suggestions, 
