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Fig. 17. — In October, 1956, globular oily hyphae (arrows) of Rhabdocline pseu- 

 dotsugae were readily apparent in the mesophyll cells. Many of these cells were 

 partially collapsed and their contents were blackened. (X 1200) 



epithelial cells and entered the resin canals. Brown (7) and Van 

 Yloten (63) stated that hyphae were never observed within the 

 endodermis. In this study large accumulations of hyphae were com- 

 monly observed around the endodermal ring (Fig. 18). Some strands 

 appeared to penetrate the outer wall of the endodermal cells, but 

 this could not be determined with certainty. The thin-walled passage 

 cells, though few in number, were definitely infected. No hyphae 

 were observed within either the transfusion tissue or fibrovas- 

 cular bundle. 



By early April, the fine intercellular hyphae in the cells of the 

 upper mesophyll were turgid (Fig. 19), were relatively thick-walled 

 and more regular in diameter than during the winter months. The 

 cells of the upper portion of the needle were mostly deteriorated. 

 The chlorenchyma adjacent to the lower epidermis was often intact 

 though filled with the globular type hyphae (Fig. 20). By late April 



47 



