N. E. Stevens — New Jersey Palmoxylon. 



427 



later spread to the roots. In fact, as shown below, the cortical 

 portions of the root were in an unusual state of preservation, 

 which might indicate that infection of the roots had taken place 

 only a comparatively short time before silicification. 



That abundant hyphse of a wood-destroying fungus should 

 be found in tissue apparently very little injured is quite in 

 accord with the mode of growth of these fungi. The writer 

 has observed that Polystictus versicolor, growing in pure cul- 



Figs. 7-11. 



Fig. 7. An " oblique " bundle showing the bast region and the xyiem con- 

 taining large peripheral vessels and a group of numerous smaller vessels 

 separated from the large ones by a zone of parenchyma, x 65. 



Fig. 8. Longitudinal section of a portion of a small stem-vessel, showing 

 tyloses. x 150. 



Fig. 9. Cross section of a root vessel, showing tyloses. x 150. 



Fig. 10. Longitudinal section of a portion of a stem-vessel, showing 

 fungus hyphae. x 150. 



Fig. 11. Cross section of a root vessel showing fungus hyphse. x 150. 



ture on sapwood of Liriodendron tuliprfera, develops a con- 

 siderable mycelium extending through most of the woody 

 tissue long before any marked effect on the lignified walls is 

 apparent under the microscope. The fossil fungus noted here 

 had apparently reached just this stage, having developed a 

 considerable mycelium and destroyed much of the phloem, 

 without affecting to any extent the more resistant tissues of 

 the vessels and sclerenchyma. 



