2o8 Transactions British Mycological Society. 



With fungus S two seedlings were attacked on the 8th day, six 

 were collapsing on the nth day and all were collapsing on the 

 I2th day. 



With fungus A all seedlings were healthy until the 12th day 

 when two were slightly attacked. 



With fungus B three seedlings were attacked on the 7th day, 

 dying on the 8th day; six more were killed by the nth day and 

 the remaining three were attacked on the 12th day (dying later). 



With fungus PE several seedlings were attacked on the 5th 

 day, all were in a collapsed state on the 6th day, and all were 

 dead on the 7th day. 



With fungus PO one seedling was attacked on the 8th day; 

 all seedhngs were dead on the nth day. 



All the seedhngs in the controls remained healthy throughout 

 the experiment. 



The result as given in the above table gives a good indication 

 of how these fungi stand in regard to their parasitism of cress 

 seedhngs under such conditions. It would, however, be more 

 accurate if the results were considered from the date when the 

 attack commenced, otherwise it is misleading in regard to PO, 

 and 5, which took a few days to commence the attack and then 

 proceeded as rapidly as E and PE. There is no marked difference, 

 therefore, between E, S, PE and PO, which were the most active 

 as parasites. B is also an active parasite of cress seedlings but 

 as already stated it is not such a fast grower as E, S, PE and PO. 

 I and A are not so active as parasites. There does not seem to 

 be any indication of a correlation between the rate of growth 

 and the rate at which seedlings are killed since / is a faster 

 grower than B. On the other hand, rapidity of growth does 

 obviously assist a fungus to cause more damage than the slower 

 grower when both are equally active parasites, vide E, S, PE, 

 PO and B. 



The fungi were isolated from diseased cress seedlings in all 

 cases with a view to ascertaining whether the diagnostic characters 

 would again be shown in culture. There was no difference in 

 growth between any form before and after passing through cress, 

 so it is reasonable to consider these characters as being permanent 

 in the sense that the term can be applied to microscopic fungi. 



The above experiment was repeated in all detail with the 

 fungi E, PE, A , B and 5, with the following results : 



With fungus E all seedlings were collapsing on the 4th day 

 after infection, and all were dead on the 5th day. 



With fungus PE the results were similar to E. 



With fungus A all seedlings were healthy on the 5th day, two 

 were dead and two diseased on the 8th day. 



With fungus B three seedlings were diseased on the 4th day, 



