137 
spore-formation of Acrospeira mirabilis. 
If the chlamydospores were sown on a watery extract of chest- 
nuts made up with agar-agar a further crop of chlamydospores was 
produced and at the same time the submerged hyphae formed 
small bunches of flask-shaped structures from which endoconidia 
arose. The more dilute the chestnut extract the greater was the 
abundance of these endoconidia, so that on germinating the 
chlamydospores in water or in agar-agar practically a pure culture 
of them could be obtained. 
When the chlamydospores were germinated in beer-wort gela- 
tine however no sign of these endoconidia could be found on the 
submerged hyphae but they became shortly septated into barrel- 
like cells, some of which grew rapidly into large ellipsoidal 
structures in which the protoplasm became finely vacuolated 
while the walls thickened and became carbonized. On placing 
these structures in water they cracked in the course of a few days 
and let free swarms of minute, slightly motile, spherical bodies. 
Presumably these structures were sporangia but so far all attempts 
to germinate the “ spores” have failed. At the same time the 
aerial portions of the mycelium again formed the characteristic 
chlamydospores. Sowings on gelatine or agar-agar made up with 
Klebs’ solution and 5 °/ 0 cane sugar or glucose gave rise to pure 
cultures of these “ sporangia.” 
In cultures on chestnut-agar five weeks or more old or in the 
cotton-wool plugs, used to keep the chestnut cultures moist, a 
further spore-form has been produced which consists of a group of 
chlamydospores surrounded by a thick envelope of several layers 
of cells. They arise from the same coils as the chlamydospores 
already described when little nutriment is available. 
These spore-balls have been germinated on the media pre- 
viously used with the following results : on pea-extract the 
mycelium was sterile, on chestnut-agar endoconidia were produced 
but not so abundantly, and on beer-wort gelatine “sporangia.” 
On the two first media numbers of cell- fusions occurred especially 
when the food supply was limited. At the same time on the 
chestnut-agar large crops of spore-balls were produced but they 
differed from those formed on the old chestnut cultures in having 
only a single layer of envelope cells — like a typical Urocystis. I 
have since found this same form in diseased chestnuts, so it must 
be assumed to be the normal one. The development of the 
abnormal form will be considered later. 
The cultures on beer- wort gelatine besides forming “sporangia” 
gave rise to arches or spirals of cells which became strongly 
swollen and carbonized. They resembled the ascogonia described 
by Tulasne and others in Ascobolus 1 and were externally very 
1 Tulasne, Anns. Sci. Nat . 5me Ser. vi. p. 215. Janezewski, Bot. Zeit., 1871, 
p. 257- 
