27 
the genus Calostoma , Desv . 
plant, about 1*5 mm. thick when dry, except at the apex 
where it is thinner, and increasing to 3-4 mm. when placed 
in water. 
The red streak present in the small specimen is now seen 
to form the innermost portion of the exoperidium, and at 
the present stage of development exists in the form of red 
powder. In the earlier condition the cells forming the red 
zone are thick-walled, the substance of the walls being studded 
with numerous small red granules. Eventually the walls 
of the cells constituting this zone become mucilaginous and 
disappear, leaving the red granules in the form of a fine 
powder, thus effecting the separation of the exoperidium 
from the originally homogeneous spherical weft of hyphae. 
The innermost portion of the exoperidium consists of com- 
pactly interwoven thick-walled hyphae about 8 /x thick, not 
at all mucilaginous, and furnished with a few red granules 
which become rarer towards the outside and eventually dis- 
appear ; the hyphae at the same time becoming thinner and 
thinner owing to the diffluent walls, and at the outside entirely 
converted into a homogeneous mucilaginous jelly. 
When a section of the exoperidium has been soaked for 
some time in water, the thin hyphae forming the outer portion 
are straight, the principal branches more or less parallel 
and growing out towards the periphery after the manner 
of the palisade-tissue of a leaf, but not at all crowded and 
frequently anastomosing. Septa and clamp-connections are 
present. If a section is allowed to dry slowly under the 
microscope the external gelatinous portion contracts, the 
small hyphae at the same time becoming spirally coiled, 
straightening out again on the application of water. 
The red colouring matter is soluble in ammonic or potassic 
hydrate, agreeing in this respect with the colouring substances 
in Corticium caeruleum , C. sanguineum , and in the fungal 
element of many lichens. Owing to a slight increase in 
length of the basal portion between the exoperidium and 
endoperidium, and continued increase in size of the latter, 
the exoperidium is ruptured at the apex in an irregularly 
