Observations on the Genus Pythium (Pringsh.). 



By 



H. 9Iarsball "Ward, 9I.A., 



Fellow of Christ's College, Cambridge, Assistant Lecturer in Botany 

 at the Owens College, Victoria University. 



With Plates XXXIV, XXXV, XXXVI. 



Among the numerous species and genera of fungi which 

 have become known to science of late, tliere are perhaps none 

 more important from a biological point of view — unless 

 Bacteria be excepted — than the minute, and for a long time 

 ill-understood organisms comprising the genus Pythium, 

 founded by Pringsheim in 1858 as a group subordinate to the 

 Saprolegnise. During some recent investigations which I 

 have lately made for the purpose of obtaining a clearer insight 

 into certain obscure processes in the vegetable cell, I had the 

 good fortune to obtain material which afforded an opportunity 

 for a study of these plant-devouring fungi, under excep- 

 tionally favorable circumstances. It appears worth while, 

 therefore, to describe these observations, not only because they 

 embrace important facts of general biological interest, but also 

 because the organisms concerned have been apparently almost 

 ignored in England.^ Whether they are to be regarded as 

 morphologically of such importance as they are believed to be 

 may remain an open question until they have been further 

 examined. 



^ They are not mentioned, for instance, in Cooke's ' Handbook of British 

 Fungi ;' and the ' Micrographical Dictionary,' 3rd edition, 1875, has a very 

 insufficient note on the genus. 



VOL. XXllI. NEW SER. K K 



