PLATE 57 



A. — Plant affected with blackleg. One stem is healthy, while the other is severely 

 diseased. 



B. — Section of single upper epidermal cell of leaf and adjacent palisade cell. The 

 epidermal cell is filled with granular tanniferous material ; the palisade cell shows dis- 

 organized protoplasm, starch grains, and crystals. A small crystal is seen inside the 

 nucleus. 



C. — Section of pith cell which is transformed into a sclereid adjacent to phloem 

 fibers. The walls of the latter are very thick and strongly lignified. 



