SB MICEOSCOPIO PtJNGl. 



or lengthened out like a line j the spores nearly 

 double the length of those of the other corn-rust 

 (plate VII. fig. 144) J and not so bright in colour. 

 By intermediate forms these two rusts pass insen- 

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

 difficult to distinguish them. Both have the spores 

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

 fig. 143) 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 Eev. 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 walking through the wheat Li com- 

 pletely painted 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 grain swells in spite of it, and the 

 only efieot 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 chaflf, 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 harmless form. The 

 true rust (T. rubigo-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 fongL It may exist in company with the mildew, but it 

 iiso more frequently is developed without a trace of mildew 

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



