The boletes of Michigan, by Alexander H. Smith and Harry D. Thiers.

6

THE BOLETES OF MICHIGAN

within the normal range and have much thicker walls. A second "abnormality" which is not infrequently encountered is an extra long and
narrower than usual spore. As yet we do not know the cause for either
of these patterns of abnormality, but are inclined to wonder whether
the nuclear cycle has anything to do with them. Large basidia, twice as
large as the adjacent ones in the hymenium may produce larger spores
than the normal range, but in the few instances in which we thought
this situation occurred, the spores from the large basidia were normal in
shape. We have seen only one or two instances of spores with an
aborted side protuberance near the apex so as to produce a mittenshaped spore-usually larger than normal. All of these types of abnormality appear among colored-spored fleshy fungi generally and are not
peculiar to boletes.
Spore shape is important at the species level, and the descriptive
terms used in this work are here defined and illustrated. As mentioned,
most bolete spores are elongate (much longer than wide). If one observes a basidium bearing nearly mature spores (fig. 1), the surface of
the spore facing the extended longitudinal axis of the basidium is
termed the face view and the one at right angles to it is the profile view.
The side opposite the face is the back view, but it is seldom used in
descriptions. The spore is usually of one outline in face view and presents a quite different outline in profile view (figs. 34). For spores with
the outline shown in profile view (fig. 4) the term inequilateral is used.
If a transverse line is drawn across the spore about midway between the
two extremities, it is noted that on the line which represents the face
view (and which is referred to as the ventral line) the bulge in it is
mostly distal to the transverse line that was drawn across the spore. On
the dorsal line the widest part of the bulge is toward the proximal end
of the spores (the end that was attached to the sterigmata). Thus, in
profile view the optical section of the spore is not symmetrical. The
concavity outlined by the depression of the ventral line just distal to the
point of attachment to the sterigmata is termed the suprahilar depression (fig. 4). If this is very pronounced, as in fig. 104, we describe
the spore as inequilateral. If the depression is scarcely evident, the shape
in profile is described as obscurely inequilateral (fig. 120). A condition
between these is referred to as somewhat inequilateral (fig. 37). Most
spores fall in this last category. Spores which in face view resemble fig.
101 are termed fusiform and, if the ends are blunt, subfusiform. The
term ovate is used if the spore is broadest toward the proximal end. If
the side walls are about parallel and there is not much taper at either
end, the outline is described as oblong. Spores will usually vary across 2