6 ASCOMYCETES 



\. Asci arranged at different levels in the perithecium, sometimes forming 



skein-like masses. 4- Aspergillales, 



Asci in fascicles arising from a common level. (P^'RENOMYCETES. ) 5. 



5. Perithecia globose, scattered, without apparent ostioles, mostly attached 



to an apparent mycelium or membrane ; or flattened and ostiolate in 



one family. 5- Perisporiales. 



Perithecia with distinct ostioles. 6. 



6. Peritliecia (and stroma if present) fleshy or membranous, bright colored 



(wliite, yellow, red, or blue). 6. Hypocreales. 



Perithecia (and stroma if present) hardened, never fleshy, rarely mem- 

 branous, dark-colored (black or dark brown). 7- 



7. Walls of perithecia scarcely distinguishable from the stroma. 



7. Dothideales. 

 Perithecia with distinct walls, either free or imbedded in a stroma. 



8. Sphaeriales. 



8. Ascoma more or less completely closed at first, opening free at maturity, 



and plane, concave, or rarely convex. (Cup fungi.) 9. 



Ascoma open from the first, nomially clavate or convex, or pitted, or with 



gyrose furrows. (Morels, lorchels. ) 14. Helvellales. 



9. Ascoma long enclosed in a tough covering which becomes torn open at 



the maturity of the spores. 10. 



Ascoma soon becoming free, without special covering ; mostly fleshy 



cup-like fungi. 13. Pezizales. 



10. Ascoma mostly elongate, the cover opening by a longitudinal fis- 



sure. II. Hysteriales. 



Ascoma roundish, the cover rupturing by radiating or siellate fissures. 



12. Phacidiales. 



Order 2. SACCHAROMYCETALES. 



This group of organisms includes the yeast plants together with 

 a few other low fungi which up to this time have not been re- 

 ported from this country. The yeast plant is concerned in the 

 process of alcoholic fermentation and is equally useful in the 

 manufacture of bread and beer. Yeast plants are unicellular, 

 grow in saccharine solutions and reproduce by gemmation {PL 4, 

 f. /). Under rare circumstances, mostly when there is a sudden 

 diminution of their food supply,* they reproduce endogenously, a 



* This condition can readily be secured bv removing " top yeast" from 

 a solution in which growth is rapid, and placing it on a moist slab of plas- 

 ter pans or a fragment of unglazed porous earthenware. The endogenous 

 spore formation ought to be seen in forty-eight hours or less. 



