May 1905] Suggestions from the Study of Dairy Fungi 123 
2 . Surface. 
The comparison of hundreds of cultures of familiar species 
shows that the general appearance or texture of the adult colony 
is fairly stable. I have designated this in my description card as 
the “surface” of the colony. In comparing such surfaces two 
general types are seen: one, those in which every conidiophore or 
the vast majority of conidiophores in the growing portion of the 
colony arises directly from the submerged mycelium through 
the culture media; the other, those in which the conidiophores 
are produced as lateral branches of matted aerial hyphae. The 
first type results as a rule in a colony which lies very close to 
the substratum without loose networks of hyphae and may be 
designated as “strict;” the second, a piling up of masses of loose 
hyphae which may be called “floccose.” A strict surface may be 
close where the fructifications are barely elevated above the 
medium making a smooth area or lax if the conidiophores are 
longer and give a velvety appearance. Floccose surfaces may be 
loose or closely woven, felted or tufted, stilboid (bearing large 
coremia), stolon bearing or composed of divergent ropes of 
hyphae or aerial hyphae may be so sparingly developed as to ap¬ 
pear strict. Such a colony might be styled appressedly doccose 
or falsely strict. 
3 . Margin. 
In discussing the surface of the colony the fact was brought 
out that the borders of the rapidly growing colony show much 
more uniformity than the center which has ceased growing. 
Study of the margin in the old colony is usually valueless, but 
during rapid growth it shows how the fungus spreads in the 
substratum, the branching, septation and measurements of the 
hyphae, and the origin of all aerial structures. One has for ex¬ 
ample but to study the growing border of a single colony of the 
common Oidium (Oospora) lactis to recognize its peculiar dich¬ 
otomous branching, anywhere afterward. Two types here will 
include by far the larger number of species. One may be called 
“indeterminate.” In this group the submerged vegetative my¬ 
celium forms a distinct band beyond the aerial and fruiting por¬ 
tion. In the other for which the term “determinate” is much 
less accurate, the aerial portion travels or appears on the surface 
as fast as the vegetative mycelium spreads in the substratum. 
An indeterminate or diffuse colony will show a succession of 
fruiting branches from conidiophores with ripe fruit in the center, 
to delicate rudiments just breaking singly through the surface at 
the margin. Such a colony will show a marked tendency to spread 
all over whatever surface is offered to it. A determinate colony 
is usually restricted in growth. Fully-formed fruit will often 
be found at the very edge if the colony is strict, with a very 
