198 



TILLERS OF THE GKOUND CHAP. 



what position the fungus on the barberry occupied. 

 This was finally done in 1865 by a German botanist 

 called de Bary, who grew the little spores both 

 on wheat and on barberry, and followed out com- 

 pletely what the botanists call their life-history. 



FIG. 44. Diagrams showing Rust in Wheat. A and B, 

 stems of wheat showing the streaks of rust. 0, a part 

 of the stem magnified showing the spores protruding. 



D, a summer spore, which infects a new wheat plant. 



E, a winter spore, which infects barberry in spring. 



De Bary showed that in the late spring the 

 spores from the barberry fungus are carried by the 

 slightest puff of air to the wheat in the fields. If a 

 spore falls on a wheat or grass stem, it puts out a 

 little tube, and creeps along the surface of the stem 

 until it reaches one of the pores. By this pore the 

 tube enters the stem and then grows fast, spreading 

 out in all directions inside the stem. After a time the 



