LYMAN: STUDIES OF HYMENOMYCETES. 
161 
produces the first germ tube, which is normally followed some hours 
later by a second germ tube from the opposite end of the spore (pi. 19, 
fig. 24). The germ tubes grow rapidly into an extensive primary 
mycelium composed of small hyphae about 3 p in diameter and devoid 
of clamps. After five or six days the hyphae of the primary mycelium 
give off branches of large size which average 6 p in diameter and possess 
abundant clamps (pi. 19, fig. 25-26); these hyphae constitute the 
secondary or mature mycelium, which at first grows intermingled 
with the primary mycelium and sometimes anastomoses with it. The 
latter, however, soon loses its contents and disappears from the culture; 
it is not again produced although frequently branches of limited growth 
from the secondary mycelium resemble the primary hyphae both in 
size and in absence of clamps. This change in the character of the 
mycelium takes place regularly in all cultures and is apparently not 
influenced by the nature of the culture medium or by other external 
conditions. 
Reproduction in cultures .— No chlamydospores or chlamydosporic 
cells w T ere observed in any of the writer’s cultures; all the cells of the 
vegetative mycelium remained thin-walled, and lost their protoplasm 
with equal rapidity. In old cultures the distal ends of many cells of 
the secondary mycelium become enlarged (pi. 19, fig. 27), and some¬ 
what resemble developing chlamydospores. These enlargements, 
however, do not have thickened walls, nor is the protoplasm retained 
beyond other parts of the mycelium; they are not reproductive and 
are perhaps due to imperfect nutrition. 
Typical oidia were not observed in this species, but in drop cultures 
from six to ten days old, small conidia appear, frequently in consider¬ 
able abundance, which do not differ greatly from oidia. Moreover, 
in nutrient-agar tubes and in cultures upon sticks of wood, bulbils 
are formed in such profusion as to cover the substratum and com¬ 
pletely obliterate the mycelium. 
Finally, in old cultures, there is occasionally a development of 
basidiosporic hymenium, thus completing the life history; but, al¬ 
though normal in appearance and structure, the hymenium was always 
very limited in extent in the writer’s cultures. 
Conidia .— In drop cultures from six to ten days old, tiny conidia 
appear about the margin of the drop on clampless conidiophores 
which either arise directly from the primary mycelium, or, more 
rarely, are slender clampless branches from the secondary (pi. 19, 
