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 

 FIG. i05.-As P ergiiius. 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. If a 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 



