MILDEW AND BRAND. 53 



draughtsman to George III., and his 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 TV. fig. 58), exhibiting 

 a tuft of the bilocular spores of Pacdnia graminis 

 bursting through a piece of wheat straw. These 

 closely-packed tufts or masses of spores, when 

 examined with a common lens, seem, at first, 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 



