MILDEW AND BRAND. 53 



draiiglitsman to George III.^ and Ws exquisite 

 drawings^ both of the germination of wheat and 

 the fungi which infest it^ are marvels of artistic 

 skill. A reduced figure from part of one of his 

 drawings is given (plate IV. fig. 58)^ exhibiting 

 a tuft of the bilocular spores of Puccinia graminis 

 bursting through a piece of wheat straw. These 

 closely-packed tufts or masses of spores^ when 

 examined with a common lens^ seem_, at firsts to 

 resemble the minute sorus of some species of fern ; 

 but when seen with higher powers_, the apparent 

 resemblance gives place to something very dif- 

 ferent. The tufts consist of multitudes of stalked 

 bodies^ termed spores^ which are constricted in the 

 middle and narrowed towards either extremity. 

 The partition^ or septum_, thrown across the spore 

 at the constriction^ separates it into two portions^ 

 each of which consists of a cell-wall enclosing an 

 inner vesicle filled with the endochrome (fig. 59) or 

 granular contents^ in which a nucleus may often be 

 made out. This species of Puccinia is very com- 

 mon on all the cereals cultivated in this country^ 

 and on many of the grasses. A variety found on 

 the reed was at one time considered a distinct 

 species ; but the difference does not seem sufficient 

 to warrant a separation. However near some other of 

 the recognized species may seem to approximate in 

 the form of the spores^ a very embryo botanist will 

 not fail to observe the distinctive features in the 

 spores of the corn mildew^ and speedily recognize 



