138 



MORPHOLOG Y. 



302- The sac fungfi or ascomycetes.- 



this uncinula belongs is known as the 



-The large group of fungi to which 

 sac fungi, or ascomycetes. While 



Fig, 165. 

 Willow mildew; bit 

 of mycelium with 

 erect conidiophores, 

 bearing cbain of 

 gonidia ; gonidium at 

 left germinating. 



Fruit of willow mildew, showing hooked ap- 

 pendages. Genus uncinula. 

 Figs. 166, 167. — Perithecia (perithecium) of 

 two powdery mildews, showing escape of asci 

 containing the spores from the crushed fruit 

 bodies. 



Fig. 167. 

 Fruit body of an- 

 other mildew with 

 dichotomous appen- 

 dages. Genus 

 microsphsra. 



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. 

 Contact of an- 

 theridium and 

 carpo gonium 

 (carpogonium 

 the larger cell); 

 the beginning 

 of fertilization. 



Fig. 169. 

 Disappear- 

 ance of contact 

 walls of anthe- 

 ridium and i''o> J/O- 



Fertilized egg surrounded by 

 the enveloping threads which 

 grow np around it. 

 Figs. 168-170.— Fertilization in sphaerotheca; 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 



carpogonium, 

 and fusion of 

 the two nuclei. 



