PERONOSPORE.E 



639 



the oiigone, and discharges into the latter the contents of the 

 antherid, thus causing its protoplasmic contents or ' ocisphere ' to 

 develop into the impregnated ' ob'spore.' The further history of the 

 <>i (spore is singularly different, even in different species of the same 

 genus. In some it germinates directly into a new mycele ; in others 

 it breaks up into a number of swarm-spores or zoospores ; each of these 

 comes to rest, and after a time germinates into a new mycele. In 



B 



FIG. 477. A-G, Cystopus candidus: H, Phytophthora mfestans. A, branch of 

 mycele growing at the apex, t, with haustoria, It, between the cells of the pith of 

 Lepidium sativum; B, branch of mycele bearing gonids ; C, D, E, formation of 

 swarm-spores from gonids ; F, swarm-spores germinating ; G, swarm-spores 

 germinating on a stomate and piercing the epiderm of the stem of a potato at H. 

 After De Bary ; magnified about 400 times. From ' Outlines of Classification and 

 Special Morphology of Plants,' by Dr. K. Goebel. 



addition to the sexual organs of reproduction, many species of Perono- 

 sporea? also produce non-sexual spores or <j<>ni<ls, which are borne 011 

 special branches springing erect from the mycele, the sporophwes or 

 gonidiophores. A similar difference is exhibited in the further 

 development of these spores. Either they germinate directly in water 

 into a new mycele, or the protoplasmic contents break up into a 

 number of zoospores which germinate in the same way. In those 



