548 
material the cortical cells showed in some cases a system of narrow, thread-like 
bodies of which it was not easy to decide whether they were distinet chromato- 
phores or branches of a much divided single chro- 
matophore. In several cases a single nucleus was 
met with. 
The inner tissue consists principally of iso- 
diametric cells, increasing in diameter inwardly. The 
outer medullary cells have a structure similar to 
that of the inner cortical cells but they usually show 
two or three nuclei, and the inner cells a greater 
number. The medullary cells, in particular the larger 
inner ones, usually contain numerous small starch- 
grains and can be said to constitute a storage tissue 
(fig. 533). These cells are connected by numerous pits, 
Fis. 533. primary and secondary ones, and it may happen that 
Ceratocolux Hartzï. Section of medullar a wall separating two cells is traversed by two pits. 
ER Wau ee tesa: an A system of smaller cells situated between the 
a large storage cells and produced by budding from 
them is present in the interior of the frond: they are usually long and narrow and 
must if anything be regarded as representing a conducting tissue. Its cells are con- 
nected with the surrounding cells by secondary pits (fig. 533). It seems probable 
that these cell-rows have been interpreted by Scumirz as belonging to a parasite 
while the surrounding larger cells were supposed to belong to a hypertrophy of 
the host plant: nothing has, however, been found by me to support this inter- 
pretation. 
In the paper (1898) where I have first described the species, I have stated 
that Ceraiocolax penetrates into the medullar tissue of Phyllophora and sometimes 
even reaches the opposite face of the frond. In the 
Danish specimens I have never found the parasite 
penetrating so far into the host; usually the bound- 
ary line between the two organisms is situated 
nearly at the level of the surface of the host or 
is a little elevated towards the middle (Plate VIII, 
fig. 5). The limit is usually fairly distinct, though 
it is not always possible to say with certainty 
whether a cell belongs to the one or the other 
Fig. 534. 
Ceratocolax Hartzü. Vertical section of the 
of the two organisms. This is in particular so in marginal zone growing in the outer wall of 
sed 2 Phyllophora. The walls of the parasite are 
the central part of the limiting zone. The parasite 4 ine. The undermost cells of the parasite 
has a softer consistence than the host, and its  penetrateintothecell-wallsofthe host. 670:1. 
walls swell much more when treated with distilled 
water and various reagents; I also in some cases succeeded in obtaining a sharp 
boundary line when staining with hematoxylin after HEIDENHAIN and then with 
