CHLOROPHYCEA 159 
of a membrane of the form of a watch-glass. 
This cell then proceeds to grow out from its parent 
cell, and assumes a similar shape. The process 
is then repeated, and by this means a thallus is 
produced, generally with irregular branching, but 
sometimes having the appearance of successive 
dichotomous or verticillate branching from the apex 
of each generation of cells. 
Dictyospheria favulosa in its early state is an 
irregularly globular mass of large cells (Fig. 47c), the 
interior of the mass becoming hollow with its growth. 
It eventually bursts, and the thallus is then ir- 
regularly lobed. It consists of numerous cells in 
several layers, all of these being bound together by 
sucker-like holdfasts, short where the cells are closely 
packed, and long-stalked where they are more loosely 
aggregated. There are remarkable internal spines 
projecting from the cell-membrane into the cell- 
cavity (Fig. 472). D. sericea has a different arrange- 
ment of holdfasts, but the main points of structure 
are the same. Wille describes the origination of 
the cells of Dictyospheeria within a mother cell. This 
may be the case, but an examination of many early 
stages of D. favulosa does not bear it out. However, it 
would be in harmony with what is known of Valonia. 
The placing of Blastophysa among the Valoniacee 
is uncertain. The plants are green, very irregular, 
much lobed cells with long colourless hairs. It is 
certainly multinucleate, but its reproduction is un- 
known, and its vegetative characters inadequate for 
determining its true position. 
Siphonocladus is a simple, minute, multicellular 
