IQO TEXT-BOOK OF FUNGI 



phores originate from the mycelium, hence there appears 

 to be no objection to the assumption that the conidial 

 condition of the Phycomycetes continued to produce 

 antheridia and oogonia as it gradually evolved and passed 

 into what is known as the Ascomycetes, through such 

 groups as the Gymnoasceae. The hall-mark of the 

 Ascomycetes consists in the presence of mother-cells or 

 asci, containing the spores. The great advance of this 

 method of reproduction over that of the Phycomycetes 

 consists in the very much greater number of units spores 

 each capable of producing a new individual, as compared 

 with the sexually produced spores of the last-named family. 



In the Phycomycetes the sexual act usually results in 

 the formation of one spore, or its equivalent from the point 

 of view of producing individuals ; in Pythium, more than 

 one, but never many, whereas in the Ascomycetes hundreds 

 of spores may result. This is effected by the oospore, 

 instead of ceasing its development soon after fertilisation, 

 producing a variable number of outgrowths or hyphae, 

 each of which gives origin to asci usually producing eight 

 spores in their interior. 



During the gradual extension of the Ascomycetes many 

 new types of conidial fruit appeared. The oldest type, 

 already evolved in the Phycomycetes as single erect hyphae, 

 simple throughout or more or less branched upwards, and 

 bearing a conidium at the tip of each branchlet, are much 

 more complicated in the Ascomycetes, where the main 

 axis of the conidiophore often becomes compound, or 

 composed of an aggregation of hyphae grouped in different 

 ways in different species, the tips of the hyphae spreading 

 on every side, each tip bearing a conidium, or in several 

 instances a long chain of conidia arranged like a necklace. 



