242 SEXUAL REPRODUCTION OF ASPERGILLALES 



tremely small and numerous spores float off in the air as an 

 invisible dust and quickly germinate under favorable conditions, 

 forming new mycelia. 



The male and female gametangia have departed considerably 

 from the form shown in the cup fungi. They now appear as 

 short, slightly modified branches of the hyphae and have lost 

 the tubular outgrowth so characteristic of the Pezizales and red 



Fig. 152. Formation of spores or conidia in the Aspergillales: A, spore- 

 bearing hypha of Aspergillus. B, hypha of green mould, Peiiicillium. C, 

 one of the terminal branches of B enlarged, showing manner of spore formation. 



algae. However they become closely intertwined (Fig. 153) 

 and the ends of the branches meet, thus the mingling of the 

 gametes is made possible through a dissolution of the separating 

 walls at the tips of the gametangia. The resulting gametospore 

 remains attached to the parent plant and germinates at once, 

 forming an irregular hyphal outgrowth (Fig. 153, By s) which 

 becomes completely overgrown by the hyphae of the mycelium 

 (Fig. 153, B, C). Thus is formed a solid ascocarp or perithecium 

 (plu. perithecia), that appears to the eye as a minute grain of 

 sand. During this growth numerous lateral branches arise on 

 the hyphae derived from the gametospore and become trans- 



