280 MR. W. ARCHER ON THE MINUTE STRUCTURE AND 
bounding wall and the first transverse septum alluded to); it thus cuts off а portion 
(the outer and smaller) of doubly convex figure (? in figs. 10, 11) from the other portion 
(the inner and larger) of triangular figure, bounded, however, by two curved lines 
and one straight (7 c in figs. 10, 11). Тһе septum, concave towards the latter, and 
separating it from the original joint, possesses its minute pair of pits and stoppers; so 
does the flat septum separating off the first joint of the decurrent branch, as well as the 
subsequent septa; but there seems to be none in that septum, convex towards this 
triangular cell, which cuts off the lenticular portion alluded to. At what period this 
latter peculiar septum is formed, or for what purpose, as I have said, I could not make 
out; and it remains to me one of the puzzles connected with this plant. It seems, as it 
were, like a ** ramification-cell " which never, however, goes on to produce a branch. 
The apical cell, whose punctum vegetationis has impressed upon it the downward 
impetus, continues to grow onwards, repeatedly dividing by a transverse septum. It is 
not long ere this dependent branch begins itself to ramify ; perhaps even the very first- 
formed joint may produce а ramification-cell quite like those of the ordinary erect 
branches ; and, as in their case, often ** ramification-cells " are present that do not seem 
to go any further. When ramifications are formed, which, indeed, is still very frequent, 
they stand off more approaching a right angle than do the ordinary branches (see 
Pl XXIX. fig. 4); and they have the same “ graft-like" appearance; the subsequent 
septa are transverse, and the pits often very obscure. Towards the base of the plant 
ultimately a dense irregular plexus of branching filaments is in this manner produced. 
Drawing, in outline, of a joint of the stem from a portion of Mr. Moseley's example of Ballia callitricha. It shows 
the junction. and: eoadaptation of the two cells, their partial invagination and the seeming double bottom, the double 
pit, and the pair of stoppers thrown out of position. One of the latter appears in profile; the other exhibits its 
truncate side or that surface which is apposed to the opening of the pit. Magnified about 400 diameters. 
