xii.] PINE-BLISTER. 269 



spores on them. Many other well-established cases 

 of similar heteroecism could be quoted. 



But we must return to the Peridermium Pint. It 

 will be remembered that I expressed myself somewhat 

 cautiously regarding the Peridermium on the bark 

 (var. corticola). It appears from further investigations 

 into the life-history of this form, that it is not a mere 

 variety of the other, but a totally different species. 



Recent researches have shown that Peridermium 

 Pini (var. corticola) is totally distinct from the form 

 on Pinus Strobus, and that several species are in- 

 cluded under the former name ; while the astounding 

 discovery has been made that the latter species, 

 Pcridcrmhim Strobus, develops a totally different 

 fungus Cronartium ribicolum on the leaves of 

 Currants and Gooseberries. 



It will be seen from the foregoing that in the study 

 of the biological relationships between any one plant 

 which we happen to value because it produces timber, 

 and any other which grows in the neighbourhood, there 

 may be (and there often is) a series of problems 

 fraught with interest so deep scientifically, and so 

 important economically, that one would suppose no 

 efforts would be spared to investigate them : no 

 doubt it will be seen as time progresses that what 

 occasionally looks like apathy with regard to these 



