226 PHYLUM VII. CARPOMYCETEAE 



the microscope add iodine, which wiU stain the starch-grains 

 blue or purple, and the yeast-plants yellowish. Many of the 

 latter wiU be found in process of budding. 



(?) Repeat experiment q on page 103 for production of 

 carbon dioxide by yeast. 



(r) Spread a little "compressed" yeast on a fresh-cut slice 

 of potato or carrot; cover with a tumbler or bell-jar to keep it 

 moist; after a few days (four to eight) examine for cells which 

 are producing ascospores. 



(s) Commercial Truffles are natives of Europe, but they may 

 be obtained for study in our markets. Make thin cross- 

 sections of the large spore-fruit and examine the ascospores and 

 asci. 



Class 15. BASIDIO SPORE AE 



The Basidium Fungi 



374. The plants, or rather the fruits, of this class are 

 among the largest and most conspicuous of the fungi. 

 They are mostly saprophytes whose abundant vegetative 

 filaments {mycelium) ramify through the nourishing sub- 

 stance, and afterward give rise to the conspicuous spore 

 fruits. The spores are produced usually in 4's upon 

 slender outgrowths from the ends of enlarged cells {ha- 

 sidia), the latter usually arranged parallel to each other 

 so as to form a spore-bearing surface (hymenium), which 

 may be external (as in Toadstools) or 

 internal (as in Puff-balls). 



375. The basidia in this class are 

 here regarded as homologous with the 

 asci of the Ascosporeae. The differ- 

 ence between them is that in the asci 



Fig. 107. — Develop- /i • j.u • J l j. 



ment of basidia and the sporcs lu their development remain 



asi lospores. inside of the ascus cavity, while in the 



basidia the spores as they develop push out so as finally 



to become external. It is obvious that the ascus is the 



