FUNGI: SAC FUNGI. 



I 97 



415. Number of spores in an ascus. The ascus is the most important 

 character showing the general relationship of the members of the sac fungi. 



Fig. 227. 

 Willow mildew; Fruit of willow mildew, showing hooked 



appendages. Genus uncinula. 

 Figs. 227 228. Perithecia (perithe- 

 :ium) of two powdery mildews, showing 



bit of m y c e 1 i u 

 with erect conidio- 

 phores, bearing 



chain of gonidia' 7 ui two puwueiy imiuewt,, snowing 



miHim at left e ? ca P e , f a ?9 containing the spores from 



gonidium at 

 germinating. 



Fig. 228. 

 Fruit body of an- 

 other mildew with 

 dichotomous ap- 

 pendages. Genus 

 microsphaera. 



the crushed fruit bodies. 



While many of the powdery mildews have a variable number of spores in 



and carpogo- 

 nium (carpogo- 

 nium the larger 

 cell) ; begin- 

 ning of fertili- 

 zation. 



Fig. 231. 

 Fertilized egg surrounded 

 by the enveloping threads 

 which grow up around it 



zaon. . 



Figs. 229-231. Fertilization in sphaerotheca; one of the powdery mildews. (After 

 Harper.) 



an ascus, a large majority of the ascomycetes have just 8 spores in an 



