THE BROWN ROT 



57 



soon becomes covered with a brownish, or ash -colored 

 velvety coating, which consists of vast numbers of mi- 

 nute spores produced by the mycelium of the fungus. 

 If one of these velvety masses be shaken over a glass 

 '^ slide/' and the slide be put under the microscope, it 

 will be seen that a great many of the spores have sepa- 

 rated and fallen off, as shown in Fig. 26. The spores 

 are blown about by the wind, and when one of them 

 lodges on an unaffected plum where sufficient moisture is 



FIG. 30. 31UMMIK1). PLUMS. 



present it starts the disease again. The rotten plums 

 continue hanging upon the tree, gradually shriveling up 

 (Fig. 28), until finally they become dry and mummied 

 husks, roughened by ridges of the skin, and in this state 

 they remain on the trees through the winter (Fig. 30).* 

 On many of these mummied plums some spores will 

 adhere, even until the following spring, when they ap- 

 parently have the power of germinating ; and in all, or 

 nearly all, of them the mycelium remains in a dormant 



