268 PROCEEDINGS OF THE AMERICAN ACADEMY. 



bils in large numbers, which gradually become darker as they mature. 

 When grown on nutrient agar in large receptacles like Erlenmeyer 

 flasks, after the mycelium has covered the whole substratum with 

 powdery bulbils, new centers of growth-activity occur at different 

 points on the surface of the culture, and the radiate development 

 of the hyphae and the subsequent formation of bulbils are repeated 

 on the top of those first formed. If the flasks have plenty of nutrient 

 and do not dry up, this process may be repeated two or three times, 

 the amount of mycelium, and consequently the number of bulbils 

 formed, decreasing each time, so that eventually there appears a 

 thick powdery mass with here and there large, white, rope-like strands 

 of hyphae persisting, which is all that can be distinguishecf of the 

 mycelium. 



The bulbils are usually more or less spherical in shape, varying 

 from 52 to 88 n in diameter, although often exceeding this size, espe- 

 cially when the primordia of two happen to be so close together that 

 their hyphae intertwine, thus forming a large irregular body. The 

 individual cells are large, densely filled with granular material and 

 oil globules, spherical at first; but the central ones soon become 

 angular by pressure, while the marginal ones retain more or less their 

 original form. There is no differentiation of a cortical layer; the 

 cell wall and contents are uniform throughout, except that occasion- 

 ally some of the peripheral cells which project beyond the others lose 

 their contents, l)ut this is the exception and is probably due to age. 



The bulbils. — The hyphae which take part in the formation of the 

 bulbils become enlarged, conspicuous, and more or less contorted on 

 account of the prominence and swollen nature of the clamp-connec- 

 tions, which often occur at short intervals. The lateral branches 

 from these divide up into short cells, so that there comes to be a 

 number of almost spherical hyaline cells with fairly thick walls and 

 filled with granular material and oil globules (Figures 4-9, Plate 6). 

 During the formation of new cells, which are also spherical in shape 

 and produced by budding from the marginal ones, the central cells 

 gradually lose their original form and become angular, as a result of 

 the lateral pressure or resistance offered by the outer cells. \\'hen 

 the bulbils are nearly mature, they assume a light straw or "rusty- 

 cinnamon" color. Figure 10, Plate 6, represents a mature bulbil, 

 drawn on the same scale as the other mature forms. This method of 

 development follows very closely that described by Lyman ('07) in 

 connection with Corticium alutaccum, considered briefly below. 



Fonnaiion of basidiospores. — The basidiosporic fructification of 



