PUCCINIA POARUM 45 



Eriksson's startling hypothesis can be accepted in regard to 

 such a fungi as the Uredinales. 



The futility of Eriksson's mode of argument is seen in his 

 suggestion (1908) that "other diseases such as the American 

 Gooseberry Mildew can live within the infected shoots in a 

 form scarcely visible to oar eyes." But direct evidence against 

 the Mycoplasm Theory is accumulating. Jaczewski (1910) 

 grew seeds obtained from many much-rusted plants, but he 

 found that, when they were sown under glass and protected 

 with adequate care from all outside infection, they all produced 

 rust-free plants. Bolley, Linhart, Zukal and Klebahn had 

 similar experiences 1 . Zach (1910) on investigating leaves and 

 culms of Rye, infected with P. graminis and P. glumarum, 

 found on the outskirts of the infection-patches all the states 

 described by Eriksson, but he proved that in all of them fungal 

 hyphse were present. In fact, Eriksson himself saw and repre- 

 sented these hyphse, but calls them " radialen Strange " of his 

 supposititious " Nucleoli," the said " Nucleoli " being merely the 

 deformed remains of the nucleus of the attacked cell. As 

 Marshall Ward (1905) remarked, Eriksson merely inverts all 

 the stages of a fungus attack on a cell, and supposes the last 

 state to be the first. This error and a misinterpretation of 

 the microscopic appearances account for the whole wearisome 

 persistence in an inherently improbable hypothesis. 



Puccinia Poarum. 



The Coltsfoot and Meadow Grass Rust. 



This species is economically of no importance ; its spermo- 

 gones and secidia occur on the common Coltsfoot (Tussilago 

 Farfara), and its uredo- and teleutospore stages on species of 

 Poa, to which however they do little harm. Here, again, the 



1 This does not accord with Eriksson's experience ; but then on some of his 

 " protected " plants aphides also made their appearance, yet this does not seem 

 to have suggested to him that the zooplasm of the aphides must also have been 

 latent in the seed ! If the aphides got in, so would fungus spores, since it has 

 been proved (Butler, 1905) that uredospores are carried by them and other 

 insects. 



