108 
IOWA ACADEMY OF SCIENCE 
These specimens tend to a taller form than the former lot, as shown both by 
measurement and by general appearance. Several were distinctly umbonate at 
top. One specimen had dehisced by breaking loose of the peridium from the 
stem at its base; the peridium then split into segments and spread irregularly. 
Another had dehisced by breaking open at the apex of the stalk, followed by 
splitting and spreading of the peridium. In both the process was very irregu- 
lar, and may have been due to injury. None of the others had dehisced at all. 
Some specimens in this lot had the trama more or less suppressed on one side 
of the columella — in one case completely so — thus tending toward a continuous 
spore-bearing mass without columella. 
The spores are olive brown in color when seen in mass. They are oval in 
shape, and measure 0.005 mm. by 0.007 mm. They have smooth thick impervious 
walls. They are borne in fours, on rather long slender sterignata, upon clavate 
basidia, which at maturity are 0.006 mm. in diameter, and about 0.022 mm. long. 
The interior of this fungus can only be described as intermediate between a 
puffball and a mushroom. A stalk, (columella) which is either stuffed or hollow* 
(to use mushroom terminology) runs vertically up the center of the body and, 
joins the peridium. At base the stalk is often prolonged into the ground as in 
Collybia radicata. Prom the peridium, which is thick and fleshy, many 
anastomosing and crumpled gills extend toward the stalk. Most of these do not 
actually join the stalk, though their basidia are closely pressed against it. But 
some are actually confluent with the stalk. As Macbride has said, one would 
take the object for an abortive or unopened agaric. Sections of young speci- 
mens are remarkably like sections of a button mushroom. But the spore mass 
has a color such as is seen only in puffballs. 
Secotium may be regarded as a morphological intermediate between the 
agarics and gasteromycetes. It is a most important form as helping one to 
understand the relation of these two groups. It may be regarded as a mushroom 
arrested in the button stage, but with a complicated gill system. Let the stalk 
be suppressed, or invaded by hymenial growth— as actually happens in some of 
our specimens — and we have a real puffball. Now if the framework of the gills 
is reduced until only cottony fibres remain, we should have a Lycoperdon. 
We must not, however, assume that Secotium is really an ancestral form. It 
simply shows some of the possibilities of the knob of fungus “meristem” which 
forms the first stage of all the higher fleshy fungi. 
* Secotium agaricoides iCsern.) Holl. = C. Warnei Peck. 
* Average of 6 measurements between 40 and 50 mm. 
t Average' of 24 measurements between 30 and 50 mm. 
