596 Church — The Structure of the Thallus of 
bourhood of the cap, and the superior and inferior coronae 
may be regarded as belonging to the main axis rather than to 
the cap-rays. The marked radial arrangement of the scars 
on the corona superior of A. mediterranea seem to point 
definitely to such a correlation, and we have in addition the 
general habit and external form which in a coenocytic plant 
may be considered of some importance. Solms-Laubach 
bases his view on the presence of a certain septum formed 
within the apparent attachment of the coronae to the cap- 
rays ; it may, on the other hand, be objected that it has not 
been shown that this septum is of primary morphological 
significance, and that it necessarily implies the ‘point of origin 
of an appendage. Whether A. mediterranea may be regarded 
as representing a survival of a highly specialized and aberrant 
form of Stage I or Stage II, or not, thus correlating the cap- 
rays with the basal portions of appendages or whole append- 
ages reduced to a single segment, it is only important to 
point out here that Acetabularia must have diverged from the 
Proto-Dasycladus type at some point, and that in searching 
for this point the capacities for variation of the normal Dasy- 
cladean appendage must first be exhausted. 
Again, the fact that the swollen cortical segments of 
Stage III can neither subserve protection nor support, since 
they neither enclose the apex, nor persist on the lower 
portions of the axis, suggests that this stage marks a tendency 
to compact aggregation of the reproductive organs which are 
being developed from the specialized basal segments which 
now increase in bulk, bulge out especially on their basiscopic 
side, and thus tend to expose the maximum surface in a plane 
at right angles to the incident light (Fig. 16). A similar type 
of appendage occurs, according to Solms-Laubach 1 , in the 
life-history of Cympolia van Bossei ; while it is also probable 
that the fertile appendages of Halicoryne Wrightii may be 
placed here. The legume-like aplanosporangia of this species 
were described by Agardh rather incompletely, but such 
Annales Jard. Buitenzorg, xi, Plate VIII. 
