790 
Thomas . — Notes on Cephaleuros. 
the young stages in the development of the fertile aerial branches observed 
by Cunningham and Marshall Ward (Fig. 17). 
The nature of the cell-wall has been tested by using numerous reagents. 
The cellulose is not a simple kind, but has been impregnated with pectic 
substances. 
In some cases the Algal cell-wall itself seems to be lamellose, the 
layers being distinctly seen in stained sections (Fig. 13). 
The presence of starch is made clear by staining with iodine ; the con- 
tents of the marginal cells and of the zoosporangia stain a deep blue-black, 
all other parts take a yellow coloration. 
Oil occurs in large quantities in the cells : the oil globules could clearly 
be seen in certain preparations. 
Summary. 
In the forms described in the preceding pages, epiphytic Algal organisms 
are found to be free from infesting Fungal hyphae, which in the majority of 
previous investigations are described as occurring in association with the 
discs. 
The most salient features which characterize both a and (3 Ceylon 
plants are the method of growth and the curious loose end of the radial 
walls, owing to the formation of transverse septa, not at the extremity 
of the radial plate but at a point slightly further forward, and in the 
a form the association of the discs with the Fungal hyphae. These 
characters are, as far as may be judged from the material, very different 
from those of the Barbadoes species, with its subcuticular habit, its 
development of ‘ rhizoids ’, the presence of barren and fertile aerial hairs 
and sub-cuticular zoosporangia, and the effect which it produces on the 
tissues of the host. 
One is naturally drawn to the conclusion that this Alga represents 
a simpler stage of development than that of the Ceylon types. 
The total absence in the latter of fructifications, and the incom- 
pleteness of the story presented by the Barbadoes material, make it 
impossible to arrive at a definite conclusion with regard to the specific 
and generic position of these organisms. As far as can be judged from 
vegetative structures, the a form from Ceylon is almost indisputably the 
same as that described by Mobius as P hyllactidium tropicum , the pri- 
mary discs of Cunningham, and the early stages of Marshall Ward’s 
Alga : the Barbadoes form in many of its features resembles the older 
stages described by Marshall Ward and the intracuticular organisms of 
Hariot and Karsten. 
