On two species of Heterosporium particularly Heterosporium echinulatum 
D 
Conidia-bearing-hyphae were produced by both forms ou all media and were 
scattered regularly over the whole mycelium, they were more numerous upon glucose 
maltose and plum-juice agar than upon salep and meat-extract agar; but in the case 
of H. echinulatum the conidiophores were far more abundant than in that of H. Betae. 
The conidia produced in petri-dishes were relatively so few in number that for ino¬ 
culation purposes spores were always taken from damp-chamber cultures in which 
they were produced in relatively large numbers. 
It was always noticed that the hanging-drop-cultures produced a far greater 
number of spores in proportion to the size of the mycelia than did the cultures in 
petri-dishes, which observation is in accordance with Klebs’ conclusions. In the 
hanging-drop-cultures the nutrient-media become exhausted in a comparatively short 
space of time and the fungus is stimulated to form reproductive organs by a diminution 
of the food-supply, whereas in petri-dishes the nutrient media are practically never 
exhausted 1 ). 
H. Betae formed zones of buried pigmented hyphae upon all media, most prominent 
however, were those on salep agar which was perhaps due to the fact of the small 
amount of surface and aerial mycelia produced on this medium. These zones 
which are often observed in clean cultures of various fungi 2 ) were only produced in 
the laboratory, that is, under conditions of changing light and temperature; they were 
not formed in incubators of nearly constant temperature. H. echinulatum never produced 
zones. 
In slants of glucose agar in test-tubes H. echinulattim formed small dome shaped 
colonies of a dark grey-green colour, the central portions being covered with an aerial 
mycelium. H. Betae formed colonies much larger in area, but similar in appearance 
except for a narrow light yellow border round each. 
On pieces of sterilised potato H. echinulatum formed small humped up colonies 
of a dark green tint, covered at first with a white aerial mycelium, which later on 
changed to grey and finally to brown. 
After some weeks growth during which time the mycelium had increased somewhat 
in area and had penetrated the potato tissues a dark brown coloured skin was formed 
upon the surface. H. Betae formed colonies tw r ice as large, dome shaped, and entirely 
white due to a rich aerial mycelium. After a few days the separate colonies coalesced 
to form one large irregular growth, the aerial mycelium changed from white to a brown 
yellow and the whole growth became humped up in parts. After some weeks of growth 
a skin also formed as in the case of H. echinulatum and the aerial mycelium became 
grey brown, but not so brown as is the case with H. echinulatum whose mycelium was 
also coarser in texture. 
H. echinulatum was further grown upon sterilised leaves of Dianthus and Beta , 
and H. Betae upon sterilised Beta-\ eaves. The leaves were placed with a little water 
in test-tubes plugged with cotton wool and sterilised in steam. The tubes contained 
enough water to keep the cultures moist for several weeks. The growths were very 
similar in all three cases and were marked by a quantity of grey-green aerial mycelium. 
Upon this culture medium the colonies of H. echinulaUim were constantly larger and 
more heaped up than those of H. Betae. Upon some of the Dianthus- leaves the conidia- 
bearing-hyphae were produced in concentric circles as they always are upon living- 
leaves, but these patches were considerably larger than those met with in nature, and 
were coated with a very rich aerial mycelium which was also not the case of the di¬ 
sease spots as seen in the field. 
(See Table on p. 6.) 
2. Cultures in hanging-drops. 
Heterosporium Betae. 
1. On glucose agar. 
On the third day after inoculation of the hanging-drops the young colonies ap 
peared as pin-points to the unaided eye, and as small regularly shaped stars under a 
small magnification such as a hand lens. The germ hyphae (fig. 4, 5) were rather 
1) Klebs, Zur Physiologie der Fortpflanzung einiger Pilze, III. Allgemeine 
Betrachtungen. Pringsheims Jahrbücher, 1900, 35. 
2) See Himmelbauer in the above cited paper and the literature there given; 
also M. Munk, Centralbl. f. Bact., II, 1911, 32, p. 353. 
