138 



MORPHOLOG Y. 



302. The sac fungi or ascomycetes. — The large group of fungi to which 

 this uncinula belongs is known as the sac fungi, or ascomycetes. While 



Fig. 165. Fi S- l66 - Fig. 167. 



Willow mildew; bit Fruit of will <? w mildew, showing hooked ap- Fruit bod of an _ 



of mycelium with pendages. Genus uncinula. other mildew with 



erect conidiophores, Figs. 166, 167. — Perithecia (perithecium) of dichotomous appen- 



bearing chain of two powdery mildews, showing escape of asci dages. Genus 



gonidia ; gonidium at containing the spores from the crushed fruit microspha^ra. 



left germinating. bodies. 



many of the powdery mildews have a variable number of spores in an ascus, 

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



Fig. 169. 

 Disappear- 

 ance of contact 

 walls of anthe- 

 ridium and 

 carpogonium, 

 and fusion of 

 the two nuclei. 



Fig. 168. 

 Contact of an- 

 theridium and 

 carpo gonium 



(carpogonium ridium and Fig. 170. 



the larger cell); carpogonium, Fertilized egg surrounded by 



the beginning and fusion of the enveloping threads which 



of fertilization. the two nuclei. grow up around it. 



Figs. 168-170.— Fertilization in sphasrotheca ; one of the powdery mildews. (After Harper.) 



some have 4, others 16, and some an indefinite number. The complex struc- 

 ture of the fruit body, as well as the usually definite and limited number of 



