144 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
(especially in Nyctalis), and reach their highest development in the 
Polyporaceae, where they occur in many species, frequently forming 
definite fructifications, and nearly or quite replacing the basidiospores. 
It is probable also, that the conidia reported by Patouillard in Stereum 
discijorme, Corticium amorplmm, and Pterula multifida, and by several 
writers in species of Hydnum, are ehlamydospores. Aside from these 
doubtful cases, ehlamydospores are not known to occur in the Hydna- 
ceae, Clavariaceae, or Thelephoraceae. In distinction from oidia, 
ehlamydospores occur in the hymenium or other parts of the fructi¬ 
fication, having been found on the mycelium only in rare instances. 
(d) Conidia have been reported in all families of the Hymenomy- 
cetes, and for convenience may be divided into the following five 
classes:— 
(1) Spores formed on a promyeelium produced by the germinating 
basidiospore. This is the type of conidium most commonly seen in the 
Protobasidiomycetes, but is known only in Pachysterigma, Muciporus, 
and Radulum laetum of the Autobasidiomycetes. 
(2) Spores produced by modified basidia. Examples of this type 
are common, especially in artificial cultures and under unnatural con¬ 
ditions of growth. This modification may merely mean an increase or 
decrease in the number of spores on the basidium, as in Matruchotia; 
or it may also carry with it such a change in the shape of the basidium 
and in the character of the spores that the sporophore can no longer 
be certainly recognized as a basidium. Examples of this kind are seen 
in Corticium marchandii, and in species of Hvpochnus, Pleurotus, 
Fomes, etc. 
(3) Spores produced by branching hyphae upon the basidio-fructi- 
fieations of certain species, probably as a result of unfavorable con¬ 
ditions, particularly excessive dampness; e. g., in Stereum hirsutum, 
Pleurotus ostreatus, Polystictus versicolor, etc. These wet-weather 
spores have never been germinated and studied in cultures, and it is not 
certain whether they are produced by modified basidia as in class (2) 
above, or are true secondary spores. They are apparently not of great 
importance in the propagation of the species possessing them. 
(4) True conidia produced upon the mycelium. These are at pres¬ 
ent certainly known only in Tomentella and in Polyporus annosus. 
(5) Spores of interesting character reported in a number of species, 
but which are not sufficiently known to merit unqualified acceptance 
as polymorphic stages of Basidiomycetes; e. g., the conidia reported 
in Pistillaria, Claudopus variabilis, Poria met amor phosus, etc. 
