112 MYCOLOGY 



when the reproductive organs are formed. Non-sexual spores, or 

 conidiospores, are borne on conidiophores which may remain within 

 the host (Albugo = Cystopus), or grow beyond the surface. They may 

 be either simple or branched. These conidiospores either germinate, 

 as in Phytophthora infestans and Peronospora nivea by means of zoo- 



Fig. 35. — I, Zoosporangium of Achlya racemosa; 2, escape of zoospores; 3, fly- 

 covered by mycelium; 4, zoospores of fungus; 5, Achlya ferax with zoosporangia and 

 zoospores; 6, Achlya proUfera, 24 hours after germination of zoospores. 7, Achlya 

 monoica, with antheridia and oogonia; 8, Achlya conlorta. {After Henri Coupin, 

 Atlas des Champignons Parasites el Pathogenes de I' Homme et des Animaux, pi. xviii, 

 1909.) 



spores which escape or by the protoplasm escaping {plasmato parous), as 

 in Peronospora densa, or by germ tubes, which in some species {Perono- 

 spora lactuca) appear at the end of the spore (acroblasfic) , or at the 

 side of the conidiospore (pleuroblaslic) , as in Peronospora radii. The 

 oogonia and antheridia, which are also present, are formed in the 



