584 Church. — The Structure of the Thaltus of 
appendages are delimited by similar perforate septa, and 
detach, leaving circular attachment-scars similar to those found 
at the junction of the whole appendage with the, main axis. 
On the upper nodes the perfect appendages form a tuft of 
assimilating filaments ( { coma ’) about 2 mm. in length ; but 
further back the basal segments of the appendages alone 
persist, and these also ultimately disappearing, leave only 
their scars of attachment, which may be traced down the axis, 
becoming transversely elongated and more faintly defined on 
the lower portions, until they can be no longer accurately 
followed. On a well-grown specimen in this stage (Fig. 2), 
18 mm. in length, 79 zones were counted; this was the 
highest number observed in a plant wholly in Stage I ; 
the upper 5 nodes being in full plumage, while basal 
segments of appendages remained to a greater or less extent 
on 23 nodes, and 51 whorls of scars could be traced back 
to a distance about 2 mm. from the rhizoid portion. Twelve 
other plants, wholly in Stage I, varying in length from 
ic-18 mm., possessed 27-79 whorls of scars or else nodes 
with segments still attached. Thus an average specimen, 
13 mm. long, would have attained to 40 whorls. Specimens 
passing on to Stage II in the apical region, as a rule, showed 
scanty traces of any basal segments of appendages belonging 
to Stage I attached to the lower part of the axis, and the 
number of whorls of the first type of appendage possibly 
varies considerably; thus, one plant, 15 mm. long, passed on 
to Stage II at the 55th node; another, 11 mm. long, at the 
40th, while a specimen figured (Fig. 10), with 23 apical whorls 
more or less in Stage II, showed over 80 whorls of scars to 
within *5 mm. of the base. Again, reversion to Type I occurs 
very generally in the early development of Stage II (Fig. 10 b). 
Branching of the main axis occurs commonly in the basal 
portion below the first whorl of scars, abortive branches or 
outgrowths being found on half the young specimens ex- 
amined. In some cases, such a branch led to definite 
development (Fig. 5) ; while indications of the possibility of 
a formation of new individuals from stolon-like outgrowths, 
