HoweE: MONOSPORANGIAL DISCS IN LIAGORA 5 
ciate’’ or tripartite divisions of a tetrasporangium and structures 
of this character may have been responsible for the current 
somewhat vague and uncertain allusions to the existence of tetra- 
spores in the genus Liagora. Occasionally the arrangement of 
the first segments of the young disc suggests that of the carpels 
of an orange, sometimes in apparent contravention of the usual 
rule that a cell divides in a plane perpendicular to its longest axis. 
When the young disc develops to a manifestly flattened form 
while still in its original orientation to the parent filament, it is 
seen (Fics. 3, 4, and 6) that one of its edges is directed towards 
the filament, while the first root-hairs (Frcs. 5 and 22), ventral 
and central as regards the disc, are lateral in respect to the fila- 
ment. 
In Liagora farinosa Lamour. and L. pinnata Harv., the genetic 
connection of these discs with the Liagora is even more difficult to 
trace than in L. ceranoides and L. valida, owing, apparently, to 
the fact that the aplanospores are released from the more rigid 
mother-cell walls before germination, so that they do not germinate 
im situ. Hyaline, apparently unicellular hairs, usually several 
times as long as the diameter of the disc, arise from the dorsal 
surface and are probably always normally present in younger 
conditions at least, but owing to their delicacy and to their appar- 
ent readiness to dissolve into mucus, they are not always visible, 
especially in LZ. ceranoides, and they are not represented in our 
figures (Fics. 6 and 18) of the disc in this species. The mature 
discs are suborbicular and are more or less similar in the four 
species of Liagora in which they have thus far been observed by 
the present writer, yet they show differences corresponding to the 
peculiarities of the species of which they constitute a part. In. 
L. ceranoides and L. valida, the discs are softer, more mucous, 
and less compact than in L. farinosa and L. pinnata, in which the 
cells of the disc, like those of the assimilatory filaments of the 
main plant, have firmer, more rigid walls. In L. valida, the discs 
are thickened in the central part and often radiately unistratose 
towards the margins, while in L. ceranoides the discs give the 
impression of consisting of more than one layer of cells throughout. 
Fertile discs are mostly 90-230 u broad (not including the mucous 
envelope), though in L. farinosa, the plants of which are commonly 
