4 
W. J. Dowson, 
rences which exist between these species. The name of Heterosporium 
Betae was given to the species here described, merely to have a name for 
it, and not to increase the already large list of insufficiently described or 
scarcely destinguishable species. 
The possibility that the fungus in question might he a Cladosporium 
together with the fact that a species of Hormodendron was also found 
upon the Beta leaves raised the question of a connection between the 
two forms. Janczewski asserts that Hormodendron is another Conidial 
form of Cladosporium and this is given as being very probable by many 
of the text books 1 ). The question was not gone into very deeply; but 
both the Hormodendron species and the Heterosporium from Beta were 
cultivated in petri-dishes and in damp-chambers for some considerable 
time and on various media. Neither of them changed into the other on 
any of the different media used, but each always produced the same co¬ 
nidial form. Perithecia were also never formed. It does not seem very 
probable therefore, that there may be a conection between the two fungi in 
the sense of Janczewski. 
II. Pure Cultures. 
After the two forms had been isolated and obtained pure from other fungi and 
bacteria, they were grown as pure cultures on various agar media in petri-dishes and 
in hanging drops in order to determine what differences existed as to form and colour 
of growth between the two mycelia when growing under similar conditions. 
1. Cultures in petri-dishes. 
On all the media for the first three or four days of growth the young mycelia 
of both forms were colourless and to the naked eye presented a very similar appear¬ 
ance. Later, however, differences began to be noticeable, the most marked of which 
was the very much smaller size of the growth of H. echimilatum compared with those 
of H. Betae. From colourless, the mycelia soon changed to a light grey and finally 
to a green; but the rapidity with which the colour changes took place and the intensity 
of the final tint varied according to the species and to the nature of the nutrient 
medium. 
The general colour of the growths was due to a blending of the colours of two 
forms of the mycelium. An aerial mycelium which was either light grey or pure white, 
and a mycelium sunken in the medium whose hyphae were pigmented by an olive green 
substance in the membrane, produced together the general appearance of grey-green, 
In all media the hyphae of the sunken mycelium contained oil-drops. On salep agar 
the sunken mycelium of H. Betae was not produced for some considerable time, long 
after that of H. echimilatum had given a grey-green appearance to its mycelium; the 
final appearance of H. Betae was a light grey-green much lighter than that of 
H. echimilatum. 
The two forms on all other media except salep agar, gave rise to dome shap¬ 
ed colonies, which never extended over the whole available area of the nutrient medium. 
An abundant aerial mycelium was formed by both, and the growths became more and 
more raised up until they finally cracked the adhearing agar layers which were drawn 
up underneath the dome-like growths. Between the aerial mycelium and the agar 
layer a very dark coloured closely interwoven network of hyphae formed a tough skin 
upon the surface of the agar. In cross sections of month-old colonies of H. Betae , this 
layer was found to be very much folded upon itself, thus accounting for the humped 
up appearance of the whole growth. 
On salep agar the mycelia were much less abundant and only in the case of 
H. Betae did the growth extend over the whole area of the medium; in all other cases 
long before this happened the agar had dried up so that growth was no longer possible. 
1) Engler u. Prantl, Lindau, in Handbuch der Techn. Mycologie, p. 271. 
