212 Scientific Proceedings, Royal Dublin Society. 



second gave negative results like the first the matter was not pursued 

 further. It was thought that possibly the development of sugar was the 

 factor which influenced infection, but the matter does not appear to admit 

 of so simple an explanation. 



Varieties naturally resistant to Infection. — Seeing that dry -rot is more 

 frequently met with in some varieties than in others, it is natural to suppose 

 that certain of them are more resistant than others, and that some may even 

 be quite immune. 



Two series of infection tests were carried out with nine varieties of early 

 potatoes raised for the purpose at the temporary phytopathological station 

 at Clifden, Co. G-alway. 



The inoculations were made as previously described, and the culture used 

 was one which produced one hundred per cent, of rots in inoculations of 

 tubers of " May Queen " just previous to the experiment. Ten inoculations 

 were made in each ease, and the results are summarized in the following 

 table — 



The results point to the conclusion that at least the varieties Eclipse, 

 Windsor Castle, and Epicure, are less susceptible to attack than the other 

 varieties ; and they suggest that a systematic trial of the pathogenicity of 

 the fungus towards an extended list of varieties might yield important 

 economic results. 



Since liability to infection is influenced both by the variety of the tubers 

 used and by their degree of maturity, it follows that in any studies as to the 



