DIMORPHISM IN CONIOTHYRIUM PIRINUM SHELDON 45 1 
fruiting sectors produced typical mycelium which however never 
developed either color or fruiting bodies, although they were kept 
for two months. 
Other plates were then inoculated with spores and with mycelium 
from the fruiting sectors and with mycelium alone from the non- 
fruiting sectors. These plates were labeled II + and II — respec- 
tively. The use of plus and minus to designate different strains of a 
fungus species is not new. Blakeslee^ in 1904 applied these terms to 
Fig. 2. Plus and minus cultures of Strain II, 7 days old. This plate was 
inoculated directly from the fruiting and non-fruiting sectors of the plate culture 
in which the first variation was noticed. 
sexual strains of the Mucorineae which when bred together produced 
zygospores. Edgerton^ in 1914 followed Blakeslee's example and 
used plus and minus to differentiate strains of Glomerella which when 
grown together produced the ascogenous stage in abundance. 
The present paper deals with a fungus reproducing asexually. 
Plus and minus must therefore not be interpreted as representing 
^ Blakeslee, A. F, Proc. Amer. Acad. 40: 203-321. 1904. 
^ Edgerton, C. W. Plus and minus strains in the genus Glomerella. Amer. 
Journ. Bot. i: 244. 1914. 
