550 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



the fungus fruitings of Spondylocladium atrovirens. This view is 

 accepted by Clinton (12), Eichinger (13), Massee (14, 16), 

 Bohutinsky (17), Erikson (19), Orton (21), Melhus (22), Bailey 

 (23), O'Gara (24, 25), and others. As we shall soon show, the 

 results presented in this paper are at variance with the views 

 presented above. 



Present work. — In this investigation the writer wished to 

 determine definitely, (i) The true relationship of the sclerotia of 

 the fungus Phellomyces sclerotiophorus Frank with Spondylocladium 

 atrovirens Harz. (2) The pathogenicity of 5. atrovirens as deter- 

 mined by pure culture inoculations. To settle i and 2, it was 

 necessary to grow the organism in pure culture. Of all the 

 writers here quoted, Johnson (9) is the only one who claims to 

 have grown it on artificial media, as he says, "Under artificial 

 culture (gelatin, agar and potato) I have found that the sclerotia 

 are readily produced, but up to the present time, neither in nature 

 nor by culture, has any typical fungal fructification been observed." 

 As will be shown later, Johnson was not dealing with S. atrovirens. 

 Appel and Laubert (10) do not report having grown the organism 

 on artificial media. They obtained the fructification of S. atro- 

 virens by placing affected tubers under moist conditions. They 

 decided this fungus to be the fruiting stage of Phellomyces sclerotio- 

 phorus. The conclusion for this relationship was drawn from the 

 fairly constant presence of the sclerotia of P. sclerotiophorus on 

 spots of potatoes affected with silver scurf. 



In the fall of 1913, the writer collected a large quantity of 

 tubers which showed typical silver scurf (fig. i). The spots on 

 each tuber were carefully examined with a hand lens. These 

 tubers were all fresh and recently harvested. The sclerotia of 

 Phellomyces sclerotiophorus were present on 99 per cent of the 

 silver scurf spots. The remainder of the spots did not show any 

 sclerotia, and none of the spots in all the material showed any 

 fruitings of Spondylocladium atrovirens. A few of the infected 

 tubers were placed in moist chambers, while the remainder of the 

 material was used for cultural work. The method of isolation 

 was as follows: The tubers were first washed and cleaned in the 

 usual way. With a sharp knife, pieces of the spots were cut out, 

 one fourth of an inch deep. These jMcces were then dropped in a 

 test tube, sterilized for one minute in a solution of 1-1,000 (alcohol 



