226 МВ. W. ARCHER ОМ THE MINUTE STRUCTURE AND 
tension to which it has been subjected during the outgrowth of the latter and of the 
ramification seated on it, it becomes gradually “thinned off to nothing” and, excepting 
any little of it left higher up (the mere softened or macerated remains), totally disappears. 
Its seeming (and why I say “seeming” опу, will appear below) total disappearance is 
hastened when a ramification-cell of the second degree is formed, owing to the more 
sudden lateral diversion and increased tension of this layer caused thereby. The inner 
stratum of the free side of the ramification-cell of the first degree is deposited simul- 
taneously with, inasmuch as it is a continuation of, that septum, shutting off therefrom 
the ramification-cell of the second degree; and it is carried onwards round the interior 
of the ramification-cell of the first degree. The lower portions of this layer converge 
towards the acute base of the cell, and there, mutually apposed, seem to pass vertically 
downwards inavery compressed state ; moreover as a single layer between the outer layer 
of the base of the stem- or rachis-joint (from which we started) and an internal layer, 
which passes round the interior of the rachis-joint and at its upward parts (on both sides 
usually), it cuts off therefrom the ramification-cells of the first degree. Now when а 
secondary branch has fully grown, if we carry our examination upwards along the 
exterior ofthe primary branch (secondary rachis) immediately over the former, we see an 
outer layer somewhat sharply marked off from the inner, and this likewise * thinned off 
to nothing" upwards. Now I believe this layer was once in continuation with that below 
the subsidiary * stipule-like " branch, and whieh latter, as we saw, is (and of course 
always was) in continuation with the lower external layer of the stem- or rachis-joint 
itself; that is to say, it had been in continuation therewith prior to its having been 
forced asunder by the continued stretching and tension caused by the growth in the first 
place of the ramification-cell of the second degree, and afterwards of the branchlet seated 
thereon. Further, this upper outer layer last alluded to must have itself once formed 
part and parcel of the upper part of the original wall of the stem- or rachis-joint, 
anterior to the formation of the septum cutting off therefrom а ramification-cell of even 
the first degree—from whose expansion laterally it got its first impetus outwards, far away 
as it has now been transported from the place where it was originally deposited. And this 
is why I spoke of its seeming disappearance. Suppose now that the basal joint of à 
branch goes on to produce a ramification-cell (and a branchlet), we find immediately 
over the same a piece of external layer “ thinning off to nothing” as before; this latter, 
again, must have been, I presume, pushed up and out from the ramification-cell just 
below it, and previous to that have formed so much of the upper portion of the basal 
joint of the branch, and so on. Possibly it may be assumed that something similar 
occurs, were it traceable, in ordinary branching confervoids ; but so common is a gelatinous 
softening of the outer layers in such, that any traces of the mutual superposition 
of lamin:e get lost. ; 
On comparing this plant with examples of Ballia callitricha from the University 
herbarium, kindly placed at my disposal for comparison by Dr. Perceval Wright, one isat 
once struck by the very great difference in habit between the two. Indeed the same 
observation holds good as regards the further forms or species В. Hombroniana and 
B. Brunonia, distinguished by some from, and by others combined with В. callitricha. 
