Neomeris dumetosa, L amour. 
593 
readily granted that the primary type of Dasycladean append- 
ages is the polytomizing coenocytic filament, with constriction 
or incomplete septation at the points of origin and ramification* 
This again is morphologically of foliar nature, the whorled 
lateral appendages of Dasycladus itself being regarded by 
Nageli as definite leaves : specialization of the appendage as 
a distinct foliar member is indicated, not so much by its 
limited growth, as by its being endowed with a certain partial 
individuality which ultimately finds anatomical expression in 
the formation of perforated septa. Such septa never occur at 
the points of ramification of the main axis, and in the 6 leaves 3 
they are correlated with a deciduous habit. That the leaf 
repeats in its own ramification the same whorled type which 
obtains in the main axis, though in an abbreviated form, does 
invalidate its foliar nature ; the essential point to notice being 
that here also the secondary segments arise as simultaneous 
whorls. 
The archetype of the Dasycladaceae may therefore be 
conceived to have consisted of a main axis bearing whorls 
of several times polytomizing foliar appendages ; and these, 
after functioning as assimilating leaves, possibly became 
wholly converted into gametangia, after the manner of such 
a recent type as Bryopsis. The nearest approach to such 
a form of reproduction, within the limits of the Dasycladaceae, 
occurs in Dasycladus clavaeformis , in which, according to 
Berthold, the whole protoplasmic contents, when the repro- 
ductive stage is attained, stream into the specially formed 
gametangia. The first stage in the development of N. dumetosa 
may be regarded therefore as a recapitulation of the primitive 
‘ Proto-Dasycladus ’ type of thallus. The same stage occurs 
in the life-history of Acetabularia , in which plant the polyto- 
mizing filament may be seen at its best development, and in 
Polypkysa (Agardh, Cramer, Solms) and Halicoryne (Cramer, 
Solms); while it persists as the adult condition in Botryo- 
phora occidentalis Agardh, Chlorocladus australasicus Sender, 
and Eudasycladus clavaeformis. Of these last, Botryophora 
approaches most nearly the earlier condition of the type in its 
