29 
the genus Calostoma, Desv. 
tinous, and must be considered as homologous with the 
collenchyma-layer in Geaster. At a later stage the thick walls 
become disorganised, when a section presents the appearance 
of a loose weft of hyphae not more than 2 \x thick imbedded 
in a homogeneous mucilaginous matrix, but in reality the 
apparent hyphae are the lumina of the original thick-walled 
cells, or more correctly the few remaining contents of the 
cells, as on staining with iodine the apparent hyphae are 
seen to consist of minute granules forming a broken line ; 
and from this appearance every transition can be observed 
in young specimens to the clearly defined thick-walled cells. 
Even in old specimens where the mucilage appears perfectly 
homogeneous in water, if the latter is replaced by alcohol, 
and iodine solution afterwards added, the outlines of the 
swollen walls are seen, owing to the accumulation of iodine 
in the interstices between adjoining cells, the mucilage itself 
undergoing no change in colour. 
When young the wall of the endoperidium is of equal 
thickness throughout, but during the period of spore-for- 
mation, local growth takes place at the apex, resulting in 
the formation of an excrescence or umbo of cylindrical form, 
from 2-3 mm. high and the same across. The circumference 
of the umbo is furnished with from 5-7 deep vertical fur- 
rows situated at equal distances, so that when viewed from 
above the umbo presents the appearance of a 5-7-rayed 
star, the rays starting from a boss-like centre. At this stage 
a fine red streak appears in the median line of each vertical 
ridge separating the furrows ; these streaks are continued 
along the apical portion of the ridge and meet in the 
boss-like centre. A transverse section shows that the streaks 
extend through the entire thickness of the wall and form 
a central core down the umbo, the component hyphae under- 
going disintegration similar to that already described in the 
red zone between the exoperidium and endoperidium. This 
process results in the formation of an aperture or mouth, 
the surrounding teeth (which are subquadrate in form with 
a depressed central line corresponding to a groove on the 
