PERONOSPORM. 



259 



tlie sexual organs ; the asexual reproductive organs, on tlie 

 contrary, are on the surface of the host. 



343. — The asexual reproduction takes place in the genus 



-^c^m 



Fig. 176.— (^stopus candidus. A, branch of mycelium,/, growing at the apex, ^, 

 and giving off haustoria, A, into the cells of the pith of Lepidium sativum. B^ co- 

 nidia-bearing portions of the mycelium, with conidia in rows, C, a conidium with 

 its protoplasm divided. D, contents of conidia escaping as swarm-spores (zoospores). 

 E.t swarm-spores (zoospores), with cilia. F, germinating swarm-spores. (?, two swarm- 

 spores, sp^ germinating on u stoma and penetrating it. M^ a swarm-spore, s??, of the 

 potato disease (Peronospwa infestans) penetrating the epidermis of the potato stem ; 

 e, i, epidermis cells. X 400.— After De Bary. 



Peronospora by the mycelium inside the host producing 

 branches, which protrude through the stomata into the air ; 

 here their tips become enlarged^ and finally separated by par- 

 titions from the remaining parts of the hyphse, thus forming 



