Fig. 21. Rosellinia. necatrix. |$i ^portion jpf the^ root of an apple-tree 

 partly covered with white, fleecy mycelium 2, brown hyphae showing 

 pear-shaped swellings, X 300 ; 3, portion of an apple-tree root with sclerotia 

 bearing clusters of conidiophores, X6; 4, a single tuft of conidiophores, 

 X 70 ; 5, _ a branch of the last, bearing conidia, X 300 ; 6, stylospores 

 produced in pycnidia, X 300 (after Viala) ; 7, perithecium surrounded by 

 conidiophores, X 6 (after Viala) ; 8, ascospores, X 350 (after Viala) ; 9, a 

 sycamore infected with the fungus. The portion above ground is repre- 

 sented some fourteen days anterior to the rest. The plant is enveloped in 

 the white woolly mycelium, a, ; on the subterranean portion Rhizoctiniae^ 

 consisting of dark mycelium, b, Z>, are to be seen. Numerous sclerotia, 

 c, c, project from the surface. (After Hartig.) 





