364 Burt . — The Development of 
In passing up the wall, the band of pseudoparenchymatous 
tissue between the light portions c, c and the central column 
R (Fig. 11) becomes narrower, until finally the light portion is 
in contact with the central column. At points where the 
light portions are merely tangent to the central column, 
deeply stained pseudoparenchymatous hyphae may be found 
running upward from below in the zone next to the column, 
then crossing through the surface of contact and passing into 
the dark zone above. The portion of the hypha lying in the 
light area shows the colour characters of that area. Treatment 
of the sections by the potash method already described is 
advisable. 
It is unusual to find hyphae which can be traced for as 
long a distance as is necessary in crossing the pore, but many 
hyphae may be found which pass from the intermediate tissue 
A through the deeply staining portions — where they show the 
irregular lateral inflations of pseudoparenchymatous hyphae — 
and then into the light area c (Fig. 11). Of course the 
greater number of hyphae in a thin section can be followed 
for only a portion of such a course, when they pass out from 
the plane of the section. The relations of the intermediate 
tissue A to that of the light portion c of a pit are exhibited 
in Fig. 12, which is a section from an egg in a slightly different 
stage of development from that of Fig. 11. This light portion 
was in the upper part of the intermediate zone, and would 
probably have formed a pit. with a narrow membrane about 
its mouth. Scattered hyphae may be seen passing into c, 
Fig. 12, from the column R, but I have been unable to trace 
them on into the partition-wall k. The general connexion 
of the tissue of the pit c with the tissue A shows that it should 
be classed with that tissue — as are the chambers lower down 
the stipe — rather than with the column R. In older stages, 
when the growth of the pseudoparenchymatous walls increases 
the size of the other chambers, it also increases the capacity of 
these chambers or pits, and numerous hyphae from the central 
column R may be seen passing into them and occupying all 
available space. 
