6 
W. J. Dowson, 
Table comparing the growths of Heterosporium echinulatum 
with those of H. Betae upon various nutrient media. 
N utrien t 
medium. 
H. Betae 
general appearance. 
H. echinulatum general 
appearance. 
Plum-juice-agar. 
More green than grey, aerial 
mycelium greyish. 
More grey than green, aerial my¬ 
celium of a fine velvety nature. 
Maltose-agar. 
Snow white aerial mycelium. 
Circular in outline, light grey, 
aerial mycelium velvety as before. 
Glucose-agar. 
Irregular shape, grey-white. 
Outline circular, light grey, aerial 
mycelium as above. 
Salep-agar. 
Flat and irregular, grey-white. 
Flat and irregular, grey-green. 
Meat-extract-agar. 
Small and regular grey-white. 
Very-small, humped up grey- 
green . 
Potato. 
Colonies coalesce, white at first, 
then grey-yellow, and finally grey- 
brown. 
White first, then grey, and finally 
brown. 
longer and more branched than those produced upon plum-juice agar. On the fourth 
day the colonies appeared pinkish in colour, and measured about 1 mm in diameter. 
The hyphae which later on would produce both the aerial mycelium and the conidio- 
phores were just emerging from the agar drop into the air space of the culture (fig. 6, 7). 
The mycelium was composed 
of hyphae olive green in colour, 
closely packed together and 
running almost straight from 
the germinating spore to the 
edge of the colony the outline 
of which was very regular and 
almost circular. The greater 
part of the young mycelium 
was slightly sunk below the 
agar surface. Short, yellowish 
hyphae given off from the 
sunken mycelium invariably 
took a downward course into 
the depths of the nutrient 
medium; these short, nearly 
vertical hyphae were very noti¬ 
ceable as they were the first 
to be seen on examining the 
drop under the microscope, 
owing to the fact that they 
were nearest the objective (fig. 8 
and photomicro A). An aerial 
mycelium was produced con¬ 
sisting of long grey hyphae, 
which, however were a little 
shorter than those produced 
upon plum-juice agar. Conidia 
bearing-hyphae were at first 
few in number, long, and grew 
in the radial direction; at this 
stage the conidiophore heads consisted of not more than two chains of spores, each 
chain containing two spores (fig. 9). Later on the brown-green sunken mycelium changed 
in colour to brown, the conidiophores were in some cases long and radially directed, 
Photomicro A. Heterosporium Betae. Portion of a 
hanging-dropculture on meat-extract agar, show¬ 
ing the long coloured hyphae penetrating the sub¬ 
stratum (x 20). 
