Dec, 1909.] 



SOME APPLE DISEASES. 



115 



Fig. 6.— Microscopic structure of the scab fungus, ^.—portion of a section thru a 

 .scab spot on an apple showing the fungus ; b, .spreading under and lifting the cuti- 

 cle, a ; c, partly disorganized cells of the apple ; e, healthy cells of the apple, 

 B. — Two spore-bearing stalks (sporophores) giving rise to summer spores /. 

 C— Spores germinating. £).— Portion of a section thru an affected leaf of apple 

 which has lain on the ground over winter and has given rise to the winter spxre 

 stage ; g, spore case (perithecium) containing a bundle of spore sacs (asci). E.— 

 Two spore sacs (asci), more highly magnified, each containing 8 two-celled winter 

 spores, three of which are shown at F. (After Longyear.) 



