38 BULLETIN 380, U. S. DEPABTMENT OF AGRICULTURE. 



Endothia parasitica gave a scanty white growth of surface mycelium, with 

 several prominent pycnidial pustules clustered near the center and of a slightly 

 darker shade than the " raw sienna " of Ridgway. 1 



CULTURES ON POTATO AGAR (SLANTED TUBES). 



Potato agar was used by the Andersons (3) to distinguish Endo- 

 thia parasitica from E. fluens. The writers have used it extensively 

 and found it a very useful medium for distinguishing the species. 

 As stated in the previous paper (77, p. 11), however, unless this 

 medium was very carefully prepared it varied greatly in acidity 

 and probably in other respects, with resultant variations in the 

 behavior of the organisms. Spore production was not so abundant 

 on this medium as on many others. The preparation of this and 

 other media is described in the paper cited. 



Endothia gyrosa. — This species developed rather slowly, producing a fairly 

 abundant aerial growth, which was felty rather than fluffy. The color was 

 white, flecked with capucine buff, and no spore masses were produced. 



Endothia singularis. — This species grew even more slowly than E. gyrosa. 

 On cultures made from conidia, growth was hardly perceptible at the end 

 of three days. Mycelial cultures at the end of one week showed less growth 

 than E. gyrosa, but did not differ greatly from it in either color or texture. 

 At the end of one month the mycelium was slightly more fluffy and decidedly 

 less in amount than that of E. gyrosa. Most of the surface was a very light 

 buff color, with sometimes a few spots of capucine orange to English red. 



Endothia fluens. — Pycnospore streak cultures of this species varied some- 

 what as to the amount and time of appearance of color, probably due to the 

 variations in the acidity of the medium referred to above. Many tubes 

 showed an orange color in one week, while others produced no orange what- 

 ever. In no case did cultures of E. fluens produce the " brassy " metallic sur- 

 face appearance so characteristic of E. parasitica. Pycnidia were few and more 

 scattered than in E. parasitica and did not begin to appear until the third or 

 fourth week. A slight amount of warbler-green color sometimes appeared in the 

 medium at this age, but never so conspicuously as in E. parasitica. 



Endothia fluens mississippicnsis. — This produced a less fluffy aerial mycelium 

 along the spore streak than E. parasitica. After five or six days the fungus 

 showed an orange color by transmitted light, and was indistinguishable in 

 this respect from E. parasitica. The character of the surface was somewhat 

 different, however, and by reflected light appeared vanthine orange. When 

 two weeks old this form differed still more markedly from E. parasitica in 

 color, being grenadine red by transmitted light and showing no spore masses. 



E. longirostris. — At the end of one week this produced a white, fluffy growth 

 scattered in small patches over the surface of +be medium. This later became 

 rather close in texture, especially near the base of the agar slant. No spores 

 were produced on this medium. 



Endothia tropicalis. — At the end of one week this showed less growth than 

 E. fluens, covering about a third of the surface of the medium, while the 

 other covered nearly the entire surface. The mycelium was closely matted 

 and a very pale buff (paler than any in Ridgway). At the end of one month 



1 In the descriptions of cultures comparisons were necessarily made with cultures in 

 flasks or tubes. This of course made comparison more difficult and somewhat less accurate 

 than if the material had been removed from the container. 



