FUNGI OF IMPORTANCE IX THE DECAY OF TIMBERS. 27 
(Buller, 6. p. 428; 7, p. 6; and Jaczewski, 26, p. 407). Under these 
circumstances the question naturally arises whether or not secondary 
spores might be produced by some of these organisms and thus ac- 
count for the rapidity with which decay spreads in certain types of 
buildings. In certain places in mills, as basements and between 
floors, for example, light may be insufficient for fruit-body forma- 
tion, yet this lack of light and the abundance of moisture would be 
highly favorable for the growth of superficial mycelium, and hence, 
perhaps, for the production of secondary spores. With these possi- 
bilities in mind, considerable attention was paid to the observation 
and study of the secondary spores formed by the five organisms in 
question. 
REVIEW OF THE LITERATURE OF SECONDARY SPORE FORMATION. 
GENERAL SUMMAEY. 
The subject matter relative to secondary spores has been well sum- 
marized by Lyman {31). His conclusions (p. 202) were : That a ma- 
jority of the hymenomycetes have no secondary spores; that oidia 
are common among the Polyporacese and Agaricaceae and are con- 
fined to these two families; that chlamydospores occasionally occur 
in connection with the basidial fructification and are quite widely 
distributed on the mycelium of all families; and that conidia and 
other highly specialized methods of reproductions (bulbils, etc.) are 
rare and occur more frequently in the Thelephoraceee than in the 
higher families. Since Lyman's paper, only scattering references to 
secondary spores have appeared. Of these only a few are of interest 
here. Marryat {32) found chlamydospores of Pleurotus subfdlmatus 
in the vessels of wood-block cultures. Eumbold {W) not only re- 
ported secondary spores for the first time in a few species of wood- 
destroying fungi, but studied their formation, germination, and sub- 
sequent development. Falck produced two comprehensive volumes, 
one in 1909 on the decay produced by species of Lenzites {lo) and the 
other in 1912 on the decays caused by species of Merulius {16) . In 
these he takes up in a thorough way the occurrence, the methods and 
conditions of formation, and the germination under various conditions 
of the oidia in the species considered. In the later work {16, p. 132- 
133) he makes some general remarks upon these oidia. He considers 
them of two kinds — a transition, or tiding over, form {Ubergangs- 
fiiichtform), as found in Merulius, and a true secondary form 
{Nebenfruchtform) , as found in Coniophora. The former he says 
are not formed under normal conditions {naturlicJien Verhaltmssen) 
but only when conditions become unfavorable for growth of the 
fungus. Their viability is reduced and they are capable of being 
disseminated only to a slight degree. The latter are found under 
