W. N. C. Belgravb 191 



Generally, it may be said that liquid media were not favourable I < > growth ; 

 gelatine cultures were marked by rapid and profuse mycelial growth 

 at the expense of pycnidial formation, the pycnidia when formed being 

 rudimentary ; on agar, growth was slow, but pycnidia were abundantly 

 formed. 



Potato and turnip slices did not prove good media, growth was slow 

 and pycnidial formation scanty. Carrot was highly satisfactory, large 

 tendril-producing pycnidia being rapidly formed. 



Growth on wood blocks, in the usual culture tubes, was very rapid 

 on the surface, a dense mycelial felt being produced in five days. Pene- 

 tration was how T ever slow; in one case, no hyphae were at any depth 

 greater than | inch in a block inoculated two months before; after 

 ten months penetration was complete. Pycnidia were formed in greater 

 abundance on those blocks with bark attached; the bark is split by 

 pressure from below, and through the fissures tufts of hyphae come to 

 the surface; on these, pycnidia are developed in 3-4 weeks. 



This formation of pycnidia on the surface of the medium, instead 

 of being immersed, has been noted by Aderhold (1), and ascribed to 

 the high moisture content of the air in culture vessels. 



All spores produced in artificial culture were found to be of uniform 

 size and shape, 5 yu by 1 /jl, hyaline, continuous, and sickle-shaped, thus 

 agreeing with those found in nature. 



The following is a detailed description of certain peculiarities in 

 some of the "strains" ; for convenience each strain is described by the 

 name and number of its host. 



(a) On raisin or grape-gelatine media. 



Victoria (1). Medium rapidly coloured black, hyphae remaining 

 hyaline. 



Victoria (2). Mycelium brown, no discoloration in medium. 



Victoria (3). Hyphae dark, no discoloration. 



Prince of Wales (5). Mycelium confined to the upper surface of 

 medium, forming a light-brown skin. No discoloration of medium. 



Pond's Seedling (6). No discoloration of medium. At the edge of 

 the dish a peculiar "efflorescence" of the medium takes place, due to 

 the production of snow-white, feathery aerial hyphae ; these sometimes 

 appear in a dish which is drying up. 



