222 PHYLUM VII. CARPOMYCETEAE 
(ASPERGILLALES). It is common on poorly dried speci- 
mens in the herbarium, and also on moldy hay and decay- 
ing vegetation generally. It sends up vertical branches, 
which swell at the top and bear a great number of small 
protuberances (the sterigmata), each of which produces. 
a chain of conidia. 
368. The sexual organs appear a little later than the 
conidia. The end of a branch of the plant becomes 
coiled into a hollow spiral which con- 
stitutes the oogone. From below the 
spiral an antherid grows upward, and 
brings its apex into contact with the 
upper cells of the oogone. After fer- 
tilization other branches. grow up 
around the oogone, and finally com- 
pletely enclose it, as in the Mildews, 
described above. In the meantime from the cells of the 
enclosed oogone branches bud out, and finally produce 
many eight-spored asci on their extremities; later the 
asci are dissolved, and the spore-fruit, now of a sulphur- 
yellow color, contains a multitude of loose spores. 
369. The Blue Molds (species of Penicillium) are 
related to Aspergillus. The conidial stage is a common 
Blue Mold on decaying fruit and pastry. The sexual 
organs resemble those of the herbarium-mold, and the 
spore-fruit is a minute truffle-like body as large as a 
coarse sand-grain. 
370. Yeast-plants. A still greater degradation of the 
sac-fungus type is reached in the minute plants which 
occur in yeast. Ifa bit of yeast be placed upon a glass 
slip and carefully examined under high powers of the 
microscope, there will be seen very many small roundish 
or oval cells, of a pale or whitish color. They have a 
cell-wall, but generally the nucleus is indistinct. These 
