The Hemiasci are Fungi with _sporangia_ which, _although resembling
asci_, yet have _not_, however, _a definite form and a definite number
of spores_. Besides endospores, conidia, chlamydospores and oidia are
found.
Order 1. =Ascoideaceæ.= _Ascoidea rubescens_ forms irregular,
reddish-brown masses in the sap issuing from felled Beeches. It
has _free sporangia_, which resemble asci in their structure, in
the development and ejection, and in the definite shape and size
of the spores. The formation of the sporangia takes place when
the nutriment is nearly exhausted, and resembles that of the
conidia, since they are developed from the end of a hypha which
enlarges, and the swelling becomes separated by a transverse
wall. Within the sporangia numerous spores of a cap-like form
are developed, which are set free through an opening at the
apex. Sporangia are formed successively at the apex of the
same hypha, the second commencing to develope as the first is
dehiscing. Conidia and sporangia are not formed simultaneously;
the former may be considered as closed sporangia.
Order 2. =Protomycetaceæ.= _Protomyces pachydermus_ causes
hard swellings on the stems and leaf-stalks of the Cichorieæ
(_Taraxacum_, etc.). These swellings consist of _chlamydospores_
(resting-spores), which germinate and become free, ascus-like
sporangia, with numerous small spores. In nutritive solutions
the chlamydospores form conidia with yeast-like buddings. _P.
macrosporus_ on _Ægopodium_, and other Umbelliferæ.
Order 3. =Thelebolaceæ.= _Thelebolus stercoreus_, is found
on the dung of deer, hares, and rabbits, and has _closed
sporangia_, which resemble asci in their shape and regular
construction, and in the ejection of spores. The covering
encloses only one sporangium, even where the sporangia arise
close together.
This order, by reason of the covering of the sporangia, forms the
transition from the Hemiasci to the Carpoasci, while the two first
supply an intermediate step to the Exoasci.