CH. XV.] 



MOULD-FUNGI. 



195 



spores are formed by endogenous formation. When these 

 sporangia are cylindrical or club-shaped, they include eight 

 spores, and are called asci ; the spores being ascospores. All 

 conidia or spores by germination grow into the mycelial 

 threads which become septate or subdivided into a row of 

 cylindrical cells ; these by division cause the lengthening of 

 the mycelial threads. 



FIG. 114. OIDIUM LACTIS. 

 Mycelium and spores. 



(a) Oidium lactis. Here the mycelium is composed of 

 septate branched filaments of various thicknesses. Some 

 branches of the mycelium at their ends or laterally at a sep- 

 tum produce by division a series of spherical or oval conidia- 

 spores, about 0*007 to ' 01 mm< l n g' These ultimately 

 become isolated, and then germinate into a short cylindrical 



o 2 



