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66 MISSOURI BOTANICAL GARDEN. 
the tissues of heartwood of pine, oak, ash, or similar 
woods in artificial cultures, which fact coincides with the 
observation that in nature, for some reason, the same 
thing happens, the older discolored heartwood being 
usually free from attacks by the mycelium. 
ConIDIA. 
The conidia are borne on erect or-slanting hyphae which 
branch alternately from the mycelium. They develop 
terminally in branched or simple moniliform short chains 
which are often in whorls (pl. 4,f.5). They are de- 
tached by the least movement, and in moist air fall’ 
together in agglutinated masses about the terminus of the 
hyphae, in a form which superficially resembles Cephalo- 
sporium (pl. 4, f. 6). These masses, however, are not so 
regular as the masses of conidia in the heads formed by 
Cephalosporium. The conidia bear some resemblance 
to those of Ovularia. The Cephalosporium-like clus- 
ters are always present in agar cultures after a few 
days’ growth. The conidia vary from obovate to elliptical 
or cylindrical. They measure from 8 to 12 in length, 
and from 2 to 4m in width. They are hyaline when 
young, but often become vacuolate or guttulate when old. 
They are unicellular and borne on septate hyphae which 
are from 3p to 5y in diameter. Only hyaline filaments 
bear conidia. In germination the conidia send out terminal 
germ tubes from either end (pl. 4, f. 7). 
PERITHECIA. 
The first indication of the formation of perithecia on the 
mycelium is the union of two or more filaments and the 
formation of a knotted mass. The adjacent mycelium 
changes first to a light brown color, and later to a very 
dark brown. In the center of the mass the young peri- 
thecium develops first as a globular black body, without a 
beak or neck. 
The walls of the perithecium are usually formed by one 
