THE SPORE-BASE FUNGI 501 
formed at the tips of vertical hyphze by the separation of 
individual cells as shown atc. Each of the dust-spores thus 
formed is regarded as representing a degenerate spore-case 
containing but a single spore. Minute sac-like cases contain- 
ing eight sac-spores are formed within a spherical envelope 
from the feeding hyphe. 
What appear to be male and female gametangia arise where two 
hyphe cross (Fig. 329, a, 6, c), the female coming from the lower 
hypha, the male from the upper. Fertilization has not been ob- 
served and all sexuality seems to have been lost in these plants; 
but from what we have called the female cell there are developed 
several eight-spored sacs or asci,! as they are called, while from the 
supposed male grow up a number of enveloping branches consisting 
of many short cells so crowded and joined as to make a complete 
protective envelope. 
Fungi related to the mildews and sometimes parasitic 
upon them, as shown in Fig. 328, b, d, produce very minute 
dust-spores which are crowded within a case resembling 
the envelope just described. When the sac-spores are set 
free under favorable conditions they germinate like the dust- 
spores. 
Comparing Erysibe with Coleochzete we find some significant 
resemblances which make it comparatively easy to suppose that 
fungi of this sort have descended from such algze;—the multicellular 
creeping branches of the thallus becoming multicellular creeping 
hyphe; the sporangia, dust-spores; the female gametangium de- 
veloping into a group of asci, while a neighboring cell, simulating 
the male gametangium, gives rise to an enveloping rind. These 
changes are such as might be expected in passing from the aquatic 
and sun-using mode of life to the aerial and parasitic. Ascospores 
characterize the Class Ascomycetes. 
183. The spore-base fungi (Class Basidiomycetes) are 
well represented by the mushrooms, although very many 
widely diverse forms are included among its other members. 
The common field mushroom (Figs. 119, 330) vegetates by 
subterranean hyphe feeding upon decaying organic matter 
in the soil. From this mycelium arise, finally, compact masses 
of hyphe forming fruit-bodies which soon become differ- 
entiated into a vertical stalk and a horizontally expanded 
1 As’cus < Gr. askos, bag. 
