Plate IV. 



Fig. 1. Photomicrograph of a cross section of a portion of the sap- 

 wood of llicoria, -minima (Marsh.) Britton rotted, by Coriolus prolifi- 

 cans (Fries) Murrill, showing a blaclc zone in cross section, X 100. Tli-<^ 

 wood at tlie riglit has been thoroughly decayed as the appearance of tlie 

 cell walls will testify. At the left the Avood is in the earlier stages of 

 decay and is giving rise to decomposition products upon the advance 

 of the decaj'. In the center is shown a back zone which separates the 

 portions of wood in the different stages of decay. 



Fig. 2. Photomicrograph of a radial section of a portion of the sap- 

 wood illustrated in Plate III, showing the formation of the brown 

 drops of the decomposition j^roducts in the pith ray cells, X 100. The 

 photograph was made of a portion of wood lying approximately onie- 

 half cm. within the external infiltrated portion. 



56 



