96 MICROSCOPIC FUNGI. 



or lengthened out like a line ; the spores nearly 

 double the length of those of the other corn-rust 

 (plate YII. fig. 144)^ and not so bright in colom\ 

 By intermediate forms these two rusts pass insen- 

 sibly the one into the other^ so that it is sometimes 

 difl&cult to distinguish them. Both have the spores 

 clustered together in the pustules, at first (plate YII. 

 fig. 148) attached by their peduncles, but they soon 

 become free, and are scattered like rust-powder 

 over the plant. Adverting to the attack of rust 

 upon the wheat crops to an unusual extent a few 

 years since, the Rev. M. J. Berkeley wrote as 

 follows : — 



We have seen rust more prevalent in white wheats, especially 

 in the variety called Russian white, which has red smooth chaff, 

 than we ever remember it. It is, however, confined to parti- 

 cular spots ; and while in one field not a single leaf is free, 

 insomuch that a person walkino- through the wheat Ls com- 

 pletely pamted with the spores, of a fine rust-red ; an adjoining 

 field, separated only by a hedge, has not a rusty leaf. So long, 

 however, as the rust is confined to the leaf, it is, we believe, 

 perfectly harmless. The gi'ain swells in spite of it, and the 

 onlv eftect is that the flag dies a little earlier, which is not 

 undesirable when it is too luxuriant. If, however, it gets to any 

 extent upon the chafi", much more if it attacks the seed itself, 

 as is sometimes the case, it is very mischievous. 



There is, indeed, a notion that rust is merely a form of mildew, 

 and this may be true ; but if so, it is a harndess form. The 

 true rust (T. rtibigo-vera), if a form of mildew, preserves its own 

 characters to the end, and merely presents a second form of 

 fruit, a circumstance which is exceedingly common amongst the 

 lower fungi. It may exist in company with the niddew, but it 

 also more frequently is developed without a trace of mildew 

 intermixed. As far, then, as its immediate effects upon the plant- 



