2 00 Dar bishire. — On Actinococcus and Phyllophora. 
filaments soon reach the cells of the cortex, and passing out 
between the filaments of this layer, they branch outside 
the host, and gradually the nemathecium of Actinococcus 
subcutaneus (Lyngb.) K. Rosenv. is formed on the external 
surface of the host-plant. Numerous filaments arise from the 
root-portion, and by repeated branching the internal vegetative 
portion (intramatrical filaments) and the external portion 
(extramatrical filaments) assume large dimensions (Plate XV, 
Fig. 2). The external filaments form a mass of radiating 
rows of cells, often branched 
at the base, which in the end 
give rise to the tetraspores 
(Fig. 6). 
The parasite is unable to 
pierce the outer covering of 
the host, when entering the 
latter. It can only attack 
the latter through the an- 
theridial ostioles. On the 
other hand this outer coat 
is easily pierced when the 
same filaments are passing 
out to form the nemathecia. 
Fig. 6. Actinococcus roseus (Lyngb.) this case they have a firm 
Kold. Rosenv. The shaded portion re- backing in the Solid Struc- 
presents the parasitic nemathecium ; the r 1 
lighter portion is the thallus of the host- ture of the medulla of the 
plant, n. large primary nemathecium ; 
n*. smaller secondary nemathecium just 
forming, x 40 diam. 
host-plant. The apex of a 
filament which is passing 
through the outer wall of 
the latter seems to affect the surrounding substance in a 
peculiar way. This is otherwise quite homogeneous in 
structure, but in places, where it is being pierced, it seems to 
become vacuolated. It appears to be corroded in some way 
by the attacking filament of the parasite (Plate XV, Fig. 3). 
A large number of filaments pass out of the tissue of the 
spermophore within a certain limited space (Plate XV, Fig. 4). 
On the outside of the spermophore they form dark-reddish 
