xxv.] CORN MILDEW AND BARBERRY BLIGHT. 181 



not matter what number or variety of borages they grow, 

 for however large the number may be, they are almost 

 sure to have no dEcidium upon them. dEcidium asperi- 

 folii, Pers., is so rare in Britain that during a thirty years' 

 study of fungi we have never once met with it. On 

 inquiring, as to the prevalence of this fungus in Britain, 

 of our friend Dr. M. C. Cooke, he replied that he had 

 carefully sought for it, but had only found it about two or 

 three times in twenty years. Mr. C. B. Plowright, who 

 wished to experiment with it, could not get it here at all, 

 and the illustrations in this work, Fig. 70 and Fig. 71, 

 were taken from a dead foreign example, simply because 

 no British or living specimen could be secured. Some 

 persons may think from this, that spring rust of corn 

 derives but scant benefit from a possible connection with 

 a fungus of such extraordinary rarity as ^Ecidium asperi- 

 folii, Pers. It is clear that the rust can keep in existence 

 for an indefinite time without any aid from the JEcidium. 

 Puccinia JRubigo-vera, D.C., and P. graminis, Pers., are 

 very close allies, and both grow upon the Graminece or 

 grasses ; one would have expected, therefore, that their 

 alternate ^Ecidium forms would both grow on one plant 

 or set of allied plants. We have seen, however, that 

 such is said not to be the case, as the Berberidacece and 

 Boraginacece are widely separated. 



Notwithstanding these objections we are not inclined to 

 attach undue importance to the absence of dEcidium Ber- 

 beridis, Pers., in Australia, or to the extreme rarity of 

 ^cidium asperifolii, Pers., here. The spores of these fungi 

 may possibly be more common in some other country, and 

 be carried through the air from one place to another. 

 Clouds of aphides and ladybirds have sometimes been seen 

 darkening the air and travelling towards Britain across 

 the sea from France, and spores may travel in the same 

 way or be carried by insects, birds, or man. We do not, 

 however, consider such a transport of spores, especially 

 across the ocean to Australia, probable, though not per- 



