HoweE: MONOSPORANGIAL DISCS IN LIAGORA 3 
monosporangium-bearing discs look at first sight very much like 
independent epi-endophytes. Their darker red color, their 
dorso-ventral rather than radial symmetry, and the lack of any 
obvious genetic continuity with the Liagora give plausibility to 
the very natural first impression that they are independent or- 
ganisms or perhaps obligate epiphytes of various species of the 
genus Liagora. Another plausible a priori hypothesis would be 
that they result from the germination of carpospores and represent 
a non-sexual alternating phase in the life-history of the Liagora. 
But in support of this latter hypothesis, the present writer finds 
no direct evidence at all, and the fact that in L. farinosa these 
monosporangial discs are commonly more abundant on antheridial 
than on cystocarpic plants would seem to point to its improbability. 
The truth seems to be that these discs arise from gonidia, gemmae, 
or aplanospores, derived from the terminal or subterminal cells of 
the assimilatory filaments of the Liagora, as was the view of 
Kiitzing in regard to similar structures in Liagora Turneri. Kiitz- 
ing appears to be the only one who has previously alluded to 
these structures in print and his observations appear to have been 
overlooked or ignored by subsequent writers on the genus. These 
monosporangial discs are especially common in West Indian 
specimens of Liagora ceranoides Lamour. (L. pulverulenia Ag.) 
and L. farinosa Lamour. (L. elongata Zan.), occurring on both 
antheridial and cystocarpic plants. In L. ceranoides, the gemmae 
are unicellular or bicellular, terminal or subterminal, solitary or 
concatenate, but are most frequently derived from the terminal 
(distal) cells of the assimilatory filaments. The cell enlarges, its 
contents become deeper red, its walls become soft and mucous, 
and a new cell wall is laid down inside the old one (Fics. 1 and 2). 
Sometimes the rejuvenated cell or aplanospore escapes from the 
old wall before germinating, but nearly always in this species, as 
in L. valida Harv., germination takes place, or at least begins, 
in situ. The original wall, however, becomes so tenuous that the 
aplanospore or young disc is very easily detached from its place 
of origin and even when it develops in its original position, the 
original walls dissolve so completely that it is usually very difficult 
to assure one’s self of its genetic connection with the filament from 
which it was derived. Occasionally, the cell, with its original 
