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nnately it could not be determined whether the cell masses which pro¬ 
jected into the cavity and bore a portion of the basidia are remnants 
of a ruptured tissue or whether they grow out from the inner layer of 
the wall after the formation of the cavity. 
When sown upon gelatine and a nutritive solution the spores will in 
about twenty hours swell up and produce a germ tube. This develops 
into a mycelium of short-celled hyphae whose growth soon ceases, while 
the cell contents become brown. In this way numerous more or less 
compact opaque masses of hyphae are produced, which form a resting 
condition like sclerotia and may be called resting mycelia. 
After remaining in a dry condition for some time these were again 
placed in a nutritive solution, the hyphae masses began to grow again, 
but developed directly into an interwoven tissue and after a short space 
showed no further phenomena of growth. 
But, on the contrary, if one of these resting conditions is placed on a 
leaf and kept moist the formation of pycnidia will follow. The pycnidia 
are therefore closely dependent upon the leaf, but this does not make 
them absolute parasites, siuce they only become apparent after the leaf 
is disorganized. Whether this disorganization was caused by the 
fungus or external causes is hard to say. 
As already stated, the above described pycnidia which appear on the 
leaf are produced by sowing ascospores or by a perennial mycelium. 
They will develop also, however, if the spores formed in the pycnidia 
are sown on a leaf. Under the most favorable conditions of growth a 
pycnidia-forming mycelium arises from these, but under unfavorable 
circumstances a resting mycelium. Besides this the same pycnidia oc¬ 
curred after the sowing of Cytispora spores upon a fresh leaf, the latter 
being formed in a pycnidium produced under artificial cultivation. The 
manner of development of the pycnidia on the leaf was the same in all 
cases. 
Oue important circumstance has not been mentioned. The pycnidia 
upon the leaves were in most cases accompanied by ao Acrostalagmus 
form. But sowings of the latter on fresh leaves only produced the same 
form again. 
We have now mentioned all the forms that could be obtained for 
observation which it is possible to suppose belong to the life history 
of Fenestella platani. The absolute proof of the connection between 
the ascospore and pycnidium is lacking in case of the pycnidia on the 
leaves. What has already been said makes it seem very likely that this 
stage is really connected with the Fenestella. As concerns the other 
forms, it is true that on the above grounds we can not trace the hyphae 
from the gonidiophores of the Acrostalagmus back to the ascospores, 
still less can it be done for the later appearing pycnidia of the Cytis¬ 
pora. But the regularity with which both appear in all the cultures, 
and the similarity of the cultivated Cytispora pycnidia with the natural 
ones, leave no doubt as to their connection. 
