34 DISEASES OF FIELD & GARDEN CROPS. [OH. v. 



spawn from a diseased potato to a thin slice cut from an 

 apparently sound one. If a very thin transparent slice 

 of a sound potato is placed on a glass slide, and some of 

 the spores and threads of the Fusisporium placed near the 

 edge of the apparently healthy living slice, as illustrated 

 in Fig. 10, the rapid progress of growth in the fungus 

 can be observed with ease if the material under experi- 

 ment is kept moist. The growth of the Fusisporium is 

 extremely rapid, and the production of the compound 

 spores most profuse. The small hibernating spores burst 

 and produce a perfect Fusisporium in six Jiours. The 

 mycelium appears to have the property of breaking up 

 the cell walls, of injuring the contained starch, and of 

 speedily reducing the potato to a loathsome mass of put- 

 ridity. In certain instances the presence of the Fusispo- 

 rium appears to cause the substance of the invaded potato 

 to rot and become dry. The fungi found under Fusisporium 

 are not generally considered to be capable of producing 

 putrescence of tissues, but F. Solani, Mart., is an exceptional 

 species ; the mycelial threads and the supporting threads 

 of the spores differ from typical species of the genus. A 

 profuse growth of Fusisporium Solani, Mart., when seen 

 under the microscope, looks like the surface of a field of 

 corn, the ears being represented by the closely -packed 

 Fusisporium spores. For lessening the attacks of this 

 fungus, the only known plan is to destroy all affected 

 material with fire, and not allow any decayed potato- 

 refuse to remain in the fields. 



