THE MICROSCOPE IN AETIOLOGY. 325 



A. DUST OR GERM FUNGI, CONIO OR GYMNOMYCETES. 



1. Mycoderma (Cryptococcus). The beer-yeast (Micro- 

 coccus, or Torula cerevisice) consists of round or oval color- 

 less cells containing one, and sometimes two bright nuclei 

 resembling oil-globules. New cells arise from these by 

 budding. No proper filament or mycelium is formed. 



The milk-yeast (Oidium ladis) can grow fungus-like if 

 submerged, while on the surface is a mycelium of articu- 

 lated filaments from which shoots grow up, whose cells 

 separate easily. 



Schwann, Pasteur, etc., consider the, yeast-fungi as or- 

 ganisms produced by specific germs, w^hile others regard 

 them as spores, which in the atmosphere fructify in other 

 forms. 



B. FILAMENTOUS FUNGI, HYPHOMYCETES. 



The mycelia of these are lengthened tubular cells, often 

 branching. The spores originate within or at the end of 

 filaments. Here belong the fungus of the musoardine of 

 the silkworm (Botrytis bassiana), the potato disease (Fusi- 

 porium solani), the grape disease (Oidium tuckerii), mould, 

 and the fungi occurring in diseases of skin and mucous 

 membranes. 



1. Penicillium glaucum, common mould or pencil mould, 

 forms most of the mould occurring upon vegetable de- 

 composing substances. The fruit-bearers rise from a 

 branched colorless mycelium. The points are tufted and 

 bear spherical conidia. 



2. Aspergillus glaucus, or green mould, is often found 

 with the foregoing. The fruit-filaments expand into club- 

 shaped basidia. The spores are greenish. 



3. Mucor mucedo and Mucor racemosus are found on 

 excrement and old articles of food. The bladder-like 

 swollen fruit-hyphen (columella) rises from a branched 



