FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 27 



(Buller, 6, p. 42S; 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 SUMMARY. 



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 Agaricacese 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 Thelephoracese 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 subfcHmatus 

 in the vessels of wood-block cultures. Rumbold (49) 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 (IS) and the 

 other in 1912 on the decays caused by species of Merulius (10)- 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- 

 183) he makes some general remarks upon these oidia. He considers 

 them of two kinds — a transition, or tiding over, form (Ubergangs- 

 fruchtform) , as found in Merulius, and a true secondary form 

 (Nebenfruchtform) , as found in Coniophora. The former he says 

 are not, formed under normal conditions (naturlichen Verhaltmssen) 

 hut only when conditions become unfavorable for growth of the 

 fungus. Their riability is reduced and they are capable of being 

 <-rninated only to a slight degree. The latter are found under 



