4:38 



N. E. Stevens — Petrified Palms. 



tissue, thougii able to penetrate the walls of those cells. 

 Fig. 10 shows the constriction in a hypha where it passes 

 through the wall of a host cell, a condition which has often 

 been observed and figured from living material. 



As in other fossil palm woods the h^^phaB are most 

 abundant in the cells of the fundamental tissue and in the 

 vascular eleriients, particularly the phloem, of the fibro- 

 vascular bundles. No hyphse appear in or among the 

 bast cells although repeatedly occurring in close proximity 

 to them, ^g. 9. That the fundamental tissue should be 



Fig. lU. — i'hotoiaierogiaph of fungus liypa penetrating- wall X)f cell of 

 P. cheyennense. 



attacked by the fungus while the bast regions of the 

 bundles remain unchanged is quite in accord with the 

 present action of fungi on the palms. In partly rotted 

 palm logs recently noted in Southern California the 

 fundamental tissue was almost entirely broken down, yet 

 the bast portions of the bundles were tough and morpho- 

 logically apparently unchanged. This close resemblance 

 of fossil and modern fungi in method of attack on the 

 host may well be considered as indicating that the environ- 

 ment of a fungus growing inside the stem of a palm was 

 relativelv the same ten million vears ago as it is today. 



