226 
P. C. VAN DER WOLK, 
formed between the bast and the wood but do not break their way through 
the bast and the bark. Finally in the sanie way the pycnides arise also 
in little quantity from that part of the cut surface of the slip which is 
in open air. So long as the young expanded buds have not yet died off, 
the disease is directly recognizable by the black mycelial covering of the 
cut surface, yet it is quite too late to combat with it then. The mycelium 
appears, in the pure-cultures also, in the first place as a downy inass but 
towards the time of the forming of the pycnides tliis downy covering sinks 
together, and a humid loathsome pitch-black layer of moulds appears, as 
it were a covering of wet paint, where the forming of the pycnides, which 
lasts very long, continues to run its course. 
3. I have been very successful in obtaining pure-cultures on several 
pabula, especially on boiled rice. For a finer investigation into the typical 
habitus of the mould this pabulum is but little adapted through its too 
great humidity, which conduces to the falling together of the mycelium 
which as it is this mould is too mucli addicted to. I have at length 
obtained the best results by nursing the mould on sterilized pieces of 
Cassava wood. 
Something peculiar now makes its appearance in that mycelium. 
In the mycelium threads more or less regularly arranged and for 
the most part in pretty large numbers there occur round bodies which 
at the first glance remind one of nuclei or oil drops or something similar. 
Such a thread is represented in fi- 
gure 1 a. I paid little attention to thern 
in the beginning. I busied myself 
to show that these round bodies were 
no oil, nor glycogen, nor granulose- 
like substances, nor other reserve¬ 
material. What to think off of these 
obscure bodies! I, originally remained 
to view them as something rarely 
occuring pabulum, or, that my technics 
in indicating of this reserve-material 
was fault, or, that the used reagenti 
a were not pure, a matter which 
already often liad troubled my experimental works in the laboratoria 
of the Selection-and Seed Gardens of the Department of Agriculture at 
Buitenzorg. 
• In a such sceptical frame of mind I made acquaintance with the 
discovery of Wehmer 1 ) concerning the refractive globules in the spores 
of Merulius lacrymans. This rechearch opened new points of view and 
so I spared no trouble in trying to indicate that my obscure globules 
in Stagonospora Cassavae perhaps were also drops of aetherian oil: yet 
without succes. 
Then, I did not other effort to identify the substance of these obscure 
bodies. No one moment I thought that they should betray themselves 
as spores, for therefore, as is to be seen in the figures, the seizes are 
apparently too small for being spores of a higher mould as 
Fig. 1. a Mycelium-thread of Stagono¬ 
spora Cassavae with endospores. x 650. 
b Germination of the endospores lying 
within the mycelium-thread. x650. 
1) C. Wehmer, Die Natur der lichtbrechenden Tröpfchen in den Sporen 
des Hausschwammes ( Meritlms lacrymans). Ber. D. Bot. Ges., Bd. XXIX, 1911. 
