PERONOSPORJ3. 



259 



the sexual organs ; the asexual reproductive organs, on^the 

 contrary, are on the surface of the host. 



343. The asexual reproduction takes place in the genus 



Fig. tfft.Oustopus candidus. A, branch of mycelium,/, growing at the apex, <, 

 and giving off hanatoria, h, into the cells of the pith of Lepidium sativum. , co- 

 nidia-beanng portions of the mycelium, with conidia in rows. C, aconidinm with 

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

 JS, swarm-spores (zoospores), with cilia, f, germinating swarm-spores. G, two swarm- 

 spores, sp, germinating on a stomti and penetrating it. //, a swarm-spore, fp, of the 

 potato disease (Peronostpora injestuns) pc.netrating the epidermis of the potato stem ; 

 , 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 hyphae, thus forming 



