7 $ 2 Thomas . — Notes oil Cephaleuros . 
In 1879 appeared Cunninghams monograph (2) on My coidea parasitica. 
Briefly his results are as follows : A zoospore, which is formed by the 
division and liberation of the contents of a resting oospore, comes to rest on 
the leaf surface. This rounds itself off and grows, the coloured cell- 
contents become four-lobed, and each lobe divides dichotomously. The 
cell-wall of the original spore in the meantime sends into the cell processes 
which branch. These, coalescing with each other, form a series of cells 
arranged in radiant fashion. New cells are formed by a repetition of this 
process. Ultimately the cell-walls become double and the disc becomes 
more or less divided into a series of radiating filaments. These are the 
primary discs, which are found in profusion on the surface of the host. 
Some of the cells of the primary disc may bud downwards ; the buds 
gradually penetrate the thickened cuticle and reach the layers between this 
and the inner cellulose membrane of the epidermal cell. A cell having 
reached this position divides actively in a dichotomous fashion and a mass 
of radiating filaments is formed. These are the secondary discs, consisting 
of a single layer of filaments. Later, ascending branches are developed 
which penetrate the cuticle. The ends of these become much swollen, and 
sporangia are produced from which motile zoospores escape. This is the 
method of reproduction during the rainy season. As the dry and cold 
season approaches, oogonia are formed from cells of the thallus and 
specialized slender-branched filaments become closely attached to them. 
Some of these filaments are dilated at their extremity, and the contents of 
one of the swollen ends are said to be emptied into the oogonium. The 
oospore, with its capacity of resisting unfavourable conditions, is formed as 
a result of this fusion. No rhizoids were observed by Cunningham, but 
branches were occasionally seen which forced their way between the 
epidermal cells into the inner tissues of the leaf. The presence of the Alga 
caused degeneration of the adjoining cells of the leaf, and in extreme cases 
the whole leaf became disorganized. 
I have had, through the kindness of Dr. Rendell, an opportunity 
of examining the valuable series of slides prepared by Dr. Cunningham, 
now in the possession of the British Museum (Natural History), and have 
been able to recognize many of the appearances described in the mono- 
graph. 
The Alga described by Cunningham was identified by Marshall 
Ward ( 15 ) as the gonidial constituent of the Lichen Strigula , but it may 
be perfectly autonomous. He placed it near Chroolepus , but regarded 
it as belonging to a distinct line of development. The Alga is at first 
a simple plate-like disc as described by Cunningham. In maturer stages 
rhizoids occur on the lower surface, zoosporangia sunk in the thallus 
are developed, which he regarded as corresponding to the structures 
described as oogonia by Cunningham. Nothing resembling a sexual 
