196 DISEASES OF FIELD & GARDEN CROPS. [CH. 



same host plant; but the botanists, who physiologically 

 connect Puccinia and ^Ecidium, say the Uredo, Puccinia, 

 and ^Ecidium in this instance are not related, and that the 

 Puccinia found on Allium ursinum, L., and A. oleraceum, 

 L., both named P. allii, are also distinct from each 

 other. They say the dEcidium produces, not the Puc- 

 cinia on its own leaves, but the Puccinia named P. 

 sessilis, Sch., peculiar to Phalaris arundinacea, L. The 

 ^cidium is abundant in Britain, but the Puccinia) which 

 should be equally abundant, or nearly so, if one parasite 

 gives rise to the other, is here extremely rare or unknown. 

 The JEcidium state of P. allii, Eud., is also said to be 

 unknown, and as the Puccinia which commonly accom- 

 panies it is said to be foreign to it, as no doubt it is, the 

 case must be a clear one of simple consortism. ^Ecidium 

 Berberidis, Pers., is not the only dEcidium found on the 

 Berberidacece. There is a second large -spored ^cidium 

 which grows on Berberis glauca, D.C., in Chili, in company 

 on the same disease spots with a Puccinia named P. 

 Berberidis, Mont. In Europe the same ^Ecidium possibly 

 grows on Berberis vulgaris, L. This fact seems to tell 

 against the connection of the barberry Alcidium with the 

 Puccinia of corn ; but in an effort to overcome the difficulty 

 it has been said that the spores of the Chili JEcidium are 

 larger than those of the true dEcidium Berberidis, Pers., 

 and chiefly on this account the Chilian parasite has been 

 elevated to the position of a new species. Personally, we 

 do not estimate the size of the spores in ^cidium as 

 worthy of marking specific distinction. They are extremely 

 variable in size in undoubted examples of ^. Berberidis, 

 Pers. A third early gro wing ^Ecidium also occurs on Berberis 

 ilicifolia, Forst. This is named dEcidium magelhanicum, B., 

 but its germ tubes are said not to enter the leaves of grasses. 

 If Puccinia and JEd&ium are physiologically related, 

 we have proofs that the two fungi not only arise from two 

 different kinds of eggs which are probably both sexually 

 produced, but the resulting fungi often cross consort with 



