PERONOSPORALES 



197 



Fig. 71.- — (a-/) Pythium debaryanum, Hesse, ig-s) P. intermedium de Bary. 

 (o) Oogonium with fully formed oosphere before fertilization, {b) Same after 

 fertilization, (c) Oogonium before fertilization, accompanied by two antheridia 

 in which differentiation into gonoplasm and periplasm has occurred, (d) Same 

 after fertilization, (e) Young oogonium. (/) Oogonium with a pair of anther- 

 idia. (g) Chain of sporangia, {h) Sporangia formed successively and becoming 

 lateral by further elongation of the hypha. (A;) Intercalary sporangium, (m-p) 

 Steps in phenomenon of extrusion of contents of sporangium into vesicle, (s) 

 Swarmspore formation. {After Atkinson 1895.) 



