24 James Stewart Wiant 



were then grown in triplicate on each of these four media for five weeks 

 at 25° C. Conspicuous differences between strains were evident on 

 Czapek's agar, and to a lesser extent on malt-extract and potato-dextrose 

 agars, while on cornmeal agar so little differentiation occurred that the 

 cultures on that medium were discarded. 



The four strains 77, 99, 141, and 177, which were selected as representing 

 the majority of those isolated at the Keene nursery, were indistinguishable 

 from one another on all three media. The principal characters of these 

 strains are: on Czapek's agar, growth poor, sclerotia absent, the aerial 

 hyphae tending to form irregular cottony tufts which are somewhat 

 appressed to the surface of the agar; on malt-extract and potato-dextrose 

 agars, growth abundant, presenting in general a buckthorn brown 5 color 

 on the former and mummy brown on the latter; sclerotia formed on those 

 two agars mostly less than one millimeter in diameter, indefinite in struc- 

 ture, for the most part only denser tufts of the fairly abundant aerial 

 mycelium and profusely scattered over the agar; on malt-extract agar 

 forming a few scattered sclerotia several millimeters in diameter, lighter 

 in color than the mycelium and distinct from the aerial part of the latter 

 (Plate II, 1-3). 



A number of other strains (13, 84, 158, 160, 172, 190, 191, and 195) 

 were similar to the above in many characters but differed from them and 

 from one another in certain minor respects. 



Several strains very distinct from all others encountered are represented 

 in these studies by strain 156. The outstanding characters of this strain 

 are: formation on Czapek's agar of numerous small compact sclerotia 

 one millimeter or less in diameter and almost black in color, distinct or 

 occasionally fused into oblong masses, always in striking contrast to the 

 white or faintly brown, thin, opaque mycelial membrane; less abundant 

 growth on malt-extract and potato-dextrose agars, with no evidence of a 

 mycelial membrane and with sclerotia fewer and chiefly confined to the 

 periphery of the agar, showing more pronounced fusion into masses on 

 malt-extract agar (Plate II, 4-6). 



An outstanding feature occurs in all of the other strains studied, namely, 

 the formation'on Czapek's agar of a very dense mycelial membrane on 

 the surface of the medium. These strains vary widely, however, in other 

 respects, as, for example, color, number, size, and type of sclerotia, and 

 abundance of mycelium. Thus, strains 155 and 187 (Plate II, 10-12), 

 which appear identical with the others, are characterized on the three 

 agars by the nearly complete absence of conspicuous sclerotia and by the 

 formation of a light-colored mycelium. Strains 167 and 175, which are 

 believed to represent a considerable number of those isolated from conifers, 

 are somewhat similar to strains 155 and 187 but differ in the formation on 

 malt-extract and potato-dextrose agars of papery sclerotia which are 



6 Colors according to Ridgway (1912). 



