PHYCOMYCETES 



25 



Fig. 17. Phytophthora infestans (Montagne) De Bary 1. Conidiophore with conidia. 

 2. Later stage, the older conidia being pushed aside. 3-6. Zoospores. 3. Enclosed 

 in the conidium. 4. The discharging of the zoospores. 5. Liberated zoospores. 

 6. Germination. (After De Bary) 



Fig. 18. Peronospora ahlnearum Casp. 

 Formation of oospore. 1. Young 

 stage. 2. Formation of oosphere and 

 fecundation-tube. 3. After fecunda- 

 tion. », antheridium ; s, oogonium. 

 350/1. (After De Bary) 



Fig. 19. Plasmopara viticola. 1. Portion of 

 diseased vine-leaf (section), with conidio- 

 phores. 2. A smaller piece. Conidiophores 

 with conidia. 3. Conidium (Sporangium). 

 4 and 5. Formation of zoospores. 

 6. Oospore. (After Millardet) 



