HEMIASCOMYCETES 



261 



Thaxter, 'The Entomophthoraceae of the United States,' 

 Memb. Boston Soc. Nat. Hist., 4, p. 133 (1888). 



Thaxter, 'Important Contributions relating to aquatic 

 Fungi, more especially the Saprolegniaceae,' Bot. Gaz., 21, 

 p. 45 (1896); 21, p. 317 (1896); 20, p. 477 (1895); 20, 

 p. 433 (1895); 19, P- 49 (1894). 



Thaxter, ' Contributions to Morphology and Classifica- 

 tion of the Zygomycetes/ Bot. Gaz., 20, p. 513 (1895); 

 24, p. i (1897). 



Wildeman, ' Census Chytridinearum ; all known species, 

 distribution, etc., includes 47 genera and 232 species,' 

 Bull. Soc. Roy. de Bot. de Bclg., 35, p. 7 (1896). 



HEMIASCOMYCETES 



This group, under the name of Hemiasci, was established 

 by Brefeld, who considers it as forming a transition between 

 Phycomycetes and Ascomycetes, due to the conversion of 

 the sporangium of the former into the ascus of the latter 

 group. Those species having a variable number of spores 

 in the ascus are here included, whereas when the spores in 

 an ascus are constant in number, usually eight, the fungus 

 belongs to the Ascomycetes proper. 



As previously stated, Harper does not admit the con- 

 version of sporangia into asci, but Harper's reasons for this 

 denial were founded on too slender evidence, and his own 

 definition of the origin of sporangiospores and ascospores 

 respectively has broken down. At the same time no one 

 has proved that the ascus is the outcome of a modified 

 sporangium, although Dangeard has indicated that a new 

 genus discovered by him, and named Protascus, but not 

 yet definitely described, is said to support Brefeld's view. 



