IJar bis hire. — On Actinococcus and Phyllophora. 259 
the outer cells of the medulla, the filaments in question being 
drawn darker, to show them up better. The drawing in itself 
is correct though misleading. It only represents a portion of 
the initial filament of the nemathecium, which in the other 
adjoining sections, had they been preserved, would have been 
seen to originate from cells just outside one of the antheridial 
cavities. Not unfrequently the spores seem later on to be 
drawn down into the antheridial cavities, and thus no trace of 
their external origin is left. 
After entering the host by the ostiole of the antheridial 
cavity, the parasite immediately branches (Plate XV, Fig. 1), 
the branches at first forcing their way into the internal 
medullary portion of the thallus of the host. Very soon 
a differentiation takes place in the primitive thallus thus 
developed. In between the cells of the medulla the filaments 
of the parasite branch and some of them grow out in the 
direction of the cortex. These form the shoot-part of the 
plant, the former acting as root-portions. The filaments do 
not enter any cells of the host, but simply force their way in 
between them along the middle lamella. In some way, 
however, they become connected with the cells of the medulla 
of the host-plant, secondary pits being formed between the 
cells of both organisms. 
The normal cells of the medulla of Phyllophora as a rule 
contain large quantities of starch. This store of food-material 
is the chief source of food for the parasite. The parasite 
therefore first of all takes possession of this starch, and in 
older plants we find that the starch of the host has disappeared 
from the cells of the medulla, the cells of the parasite now 
being filled with starch. For this reason it is easy to differen- 
tiate the two organisms by adding iodine, when the parasite 
will turn dark blue, the cell-contents of the host remaining 
unstained. 
From the filaments, which are found in the medulla of the 
host, arise, as already mentioned, the shoot-filaments. They 
grow in a direction chiefly towards the flat surface of the 
spermophores, which are infested by the parasite. The 
