Bui. 1417, U. S. Dept. of Agriculture 



PLATE I I 



A 



i* 



*v 





B 



iwhri- - K **$* <i##^ Mi 



Results of Hyph/e Invasion 



,4, Longitudinal section of an alfalfa root, showing two points of entrance near 

 together. The cork cambium can be seen almost totally invaded by the hyphae 

 at the right, while the cork cells are perfectly healthy. Note, just above, the 

 cross sections of two strands. Practically all of the parenchyma cells are invaded 

 by the fungous mycelium (X 166). B, Cross section of a lateral root of cotton 45 

 centimeters beyond the diseased portions, showing the abundance of hyphae in 

 the outer vessels of the xylem. No strands were found on the surface of these 

 roots, nor were there any indications of fungous invasion in any part of this sec- 

 tion except in the vessels shown (X 220). C, A spiral vessel in the region of the 

 rotten portion of an alfalfa root, showing the fungous hyphae within the vessel. 

 These hvpha? can apparently go down these vessels for 'some distance. See B. 

 (X630) 



