1922] Essig: Morphology of Schizophyllwm commune Fries 457 



siderable difference of opinion in the literature as regards the shape 

 and size of the spores. The early writers, such as Fries (1821), Cooke 

 (1871), and Saccardo (1887), stated that they were subglobose, about 

 2.5(1. in diameter. Morgan (1890) called attention to the fact that 

 the spores he had been examining averaged 5-6 by 2.5/^, and won- 

 dered if a mistake had been made, or if his were possibly a different 

 species. The possibility of a different species seems unlikely, for later 

 Hennings (1898) and Eumbold (1910) in Europe and Murrill (1915) 

 in America have found them to be oblong, at least twice as long as 

 broad. It is possible that the globular bodies supposed by the early 

 writers to be spores were nothing but the peculiar structures which 

 are shed by the dried sporophores when first they are wetted to obtain 

 a spore print. These bodies and no spores are dropped by old her- 

 barium specimens, which have lost their vitality, when they are mois- 

 tened. The spores occasionally possess small vacuoles. No oil drop- 

 lets have been demonstrated. The wall is thin. The spores are densely 

 filled with protoplasm. At shedding time two nuclei are present 

 (fig. 7, pi. 54). 



The number of nuclei in the spores of the Hymenomycetes so far 

 examined is either one or two. One was found in the spore of Hypoch- 

 nus subtilis (Harper, 1902), Amanita vaginatcu, Tricholoma virgatum, 

 and Cantharellus infundibuUformis (Rosenvinge, 1886), while two 

 were found in Craterellus cornucopioides, Clavaria vermicutaris, Bole- 

 tus edulis, and £. variegatus (Rosenvinge, 1886). Maire (1900), after 

 studying some thirty species, stated that there might be either one or 

 two nuclei in a spore. In the case of two nuclei, the single nucleus 

 divides as soon as it enters the spore from the basidium, instead of 

 just preceding the first segmentation during spore germination. 



Spores germinate readily in water and in a great variety of culture 

 media. The spores first swell to nearly twice the normal size ; then a 

 germ tube appears at either one or both ends (fig. 8, pi. 54). The 

 width of the germ tube often approximates that of the spore, and as 

 a result the identity of the spore may soon be lost. The length that 

 the tube attains prior to segmentation depends to a certain extent 

 upon the nature of the culture medium, segmentation occurring earlier 

 when the medium is rich in food materials. In tap water growth 

 ceases about the time the first septum and branch appear. Branching 

 may occur either before or after the first septum is laid down, but it 

 usually occurs about that time. 



