PEUONOSPOR^. 



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 



Fig. 176. — Cystopus candid/us. A, branch of mycelium, f, growing at the rfpex, i, 

 and giving off liaustoria, h, inlo tlie cella of the pith of Lepidium sativwm, B, co- 

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

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

 jF, swarm-spores (zoospores), with cilia. J^, i^ermiiiating ewarm-spores. (?, two swarm- 

 spores, SjO, germinating on a stoma and penetrating it. I/, a swarm-spore, sp, of the 

 potato disease {Peroiioepcn'a itifestcms) penetrating the epidermis of the potato stem ; 

 «, i, epidermis cella. 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 



