REPORT OF THE SOCIETY 



79 



OOSPORE-LIKE BODIES IN CULTURES OF PHYTOPHTHORA 



INFESTANS 



By H. R. Angell. 



How the fungus causing Late Blight of Potato overwinters is a problem 

 that has, we feel, not been altogether solved. The general infection that sud- 

 denl}^ appears in fields in the Fall when weather conditions are favourable has 

 not yet been satisfactorily explained and that there is some other means of over- 

 wintering than as mycelium in diseased tubers is a possibilitj'. In the seventies 

 Worthington G. Smith reported that he had found oospores in diseased tubers, 

 but DeBary disproved this. Sadebeck later showed that they were those of 

 Pythium Equiseti, while Massee expressed the opinion that they were Chlamy- 

 dospores of a Fusarium. Smorawski in a single instance found bodies that he 

 called immature oospores. Clinton, in 1910, reported that he had in pure cul- 

 tures of Phytophthora infestans found perfect oogonia, antheridia and even 

 oospores. Jones at Vermont, at the same time, announced that he had found in 

 pure cultures immature bodies apparently of an oogonial nature but whose 

 identity was doubtful. 



Individual bodies showing types of structures 



Large diameter mycelium developing oospore — like bodies in culture. 



