146 ILLINOIS ACADEMY OF SCIENCE 



that sooty blotch is common in the Guelph (Ontario) mar- 

 ket. 



In the United States, it was indicated through infor- 

 mation in the records of the Plant Disease Survey, and 

 correspondence with plant pathologists of the different 

 states, that with the possible exception of Georgia, sooty 

 blotch is present in every state east of the Mississippi 

 River, as well as the entire tier of states from north to 

 south, adjoining these Mississippi Valley states. Ne- 

 braska, Kansas, Idaho, and Washington are the only 

 other western states to report the fungus. 



Morphology. 



Methods. It was found for the purpose of the present 

 study that the best methods of securing suitable mounts 

 were the f ollomng : 



Sections bearing the fungus were cut as thin as pos- 

 sible, parallel to the surface of the fruit, using where 

 convenient, light colored varieties. These strips of epi- 

 dermis were moistened in water, then placed cuticle 

 downward, and carefully scraped to remove as much of 

 the tissue as possible, killed in absolute alcohol, dehy- 

 drated, cleared with xylol and mounted in Canada balsam. 

 Some difficulty was encountered in making accurate ob- 

 servations of the cell structures of the fungus, owing in 

 some cases to the density of the epidermal cells of the 

 host. 



Attempts to utilize the methods recommended by Stev- 

 ens (1916), that of lifting off the superficial mycelium by 

 means of a thin film of celloiden, applied and allowed to 

 dry, were successful only on certain apples. Some strik- 

 ingly good results were obtained by this method, how- 

 ever, especially in removing pycnidia. 



A third method was that of cutting microtome sections 

 lO/x in thickness, of material imbedded in paraffin. The 

 sections were fastened to the slide in the usual way, the 

 paraffin removed by xylol, the slide rinsed in alcohol and 

 then left in saf ranin stain over night. The next morning, 

 the sections were decolorized sufficientl}^ with acid alco- 

 hol, dehydrated, cleared, and mounted in balsam. The 



