240 
P. C. VAN DER WOLK, 
that had been directly infected by the “Sclerotium disease”. 
This parallelism was so striking that I immediately began a systematic 
enquiry in the direction found. Avachis and Voandzeia plants and fruits 
were sterilized in boiling water and subsequently placed in sterilized 
culture-pans, the cover-edges of which were closed with cotton-wool. 
Some of these were now infected with the above mentioned pure-cultures 
of the Sclerotium-form, others remained uninfected as control pans. 
In these uninfected control pans there was never a mould vegetation to 
be perceived, only bacteria which I could not exclude, and these bacteria, 
indeed, were very welcome! 
The infected culture pans exhibited nothing special during the first 
month; just as in the first paragraph, it appeared that the ïnould had 
need of an astonishingly long time in order to determine its real nature 
and to reveal it to man; for that the substratum must be in an advanced 
stage of decay, whereby it indeed does justice to its Ascobolus nature. 
At last the Ascobolus fruit-bodies appeared only in the infected 
pans (infected with Sclerotia) and in some here and there also already 
the Rhizo stilbell a fruit forms. 
They were the only moulds which occured in the infected 
culture-pans and as I say above, in the uninfected pans never one 
mould appeared. 
After that I brought the infection experiments to still further pre¬ 
cision. 
I laid in small PETRi-glasses only single small pieces of steri¬ 
lized stalk; ten PETRi-glasses were infected with the pure-cultured 
Sclerotium material, and ten remained uninfected as control-glasses. The 
uninfected ones all remained absolutely free from any development of 
moulds; half a month after the beginning of the experiment, the evidently 
undispensable Bacteria decayed the stalks. Of the ten infected PETRi- 
glasses nine exhibited Ascobolus fruit bodies after 1 x / 2 months. 
Indeed no further room for doubt was possible: the Ascobolus and 
the Sclerotium and the Rhizostilbella are all three forms of habitus 
of one and the same mould. 
* * 
* 
5. The Ascobolus is the highest fruit form, the chief-fruit form, of this 
mould; and I have given it the name that is most characteristic for it, 
I have called it Ascobolus parasiticus , so comprehending in it the 
highest fruit form together with the most notorious by-form, viz: the 
parasitic Sclerotium. The Ascobolus fruit-bodies as such, are generally 
recognized as typical saprophytes. Also in my cultures Ascobolus in 
narrow sense appears only as a saprophyte; it is even such a pro¬ 
nounced saprophyte that I have never met with it in free-nature: nor 
on the old dead Voandzeia nor on Aiq Avachis plants, nor on the manure 
which is used here on so large a scale in the Experimental Gardens. It 
thrives evidently only under the conditions found in a culture-pan, 
that is to say on a substratum that is utterly decayed and very 
wet. It is therefore quite peculiar that it should have an allied form of 
habitus which is pure parasitic, viz: — “the Sclerotium state.” It is 
consequently not to wondered at that one has never been able to completely 
discover this mould, since the Ascobolus and Rhizo stilbella forms are 
