132 BROOKLYN BOTANIC GARDEN MEMOIRS 



daily abundant along some of the medullary rays. It is not evenly 

 distributed. The hyphae seem to travel in fascicles and they are 

 everywhere intercellular. Sections of the wood show that there are 

 strands of parenchyma that, from appearances, would seem to be 

 burrowing through the wood, thrusting the tracheids aside as though 

 endowed with great power. These same parenchyma strands are 

 also found in the cortex. They run in almost every direction. Hyphae 

 are always associated with them. Tracheids in infected areas of the 

 wood are considerably modified. The walls are thinner, the cells are 

 prismatic and in many cases have failed to develop bordered pits. 

 The walls of such cells frequently appear to be broken down or 

 crushed in and partially disorganized. It may very well be that the 

 fungus has some power to disorganize lignified cell walls. Wherever 

 hyphae occupy the lumen of a cell it is likely to have been the result 

 of sueh mass action. There is no boring through the walls nor entering 

 tracheids through bordered pits. The "Schlafende Augen," or 

 parenchyma strands, in the cortex and along the line of medullary 

 rays in the wood as well as the patches of abnormal or partially 

 developed tracheid tissue are the result of the stimuli proceeding 

 from hyphae that were nearby at the time this tissue was being de- 

 veloped. It is difficult to understand how a cambium cell harboring 

 a hypha could divide at all, or how a tracheid could change its form 

 once it has become lignified. 



The cambium reacts in such a way as to cut off by the excessive 

 development of tracheids certain fascicles of hyphae and thus 

 check the radial and longitudinal advances of the fungus. The 

 apparently isolated patches of mycelium found in the heart wood are 

 nevertheless quite generally connected above or below with some 

 radially placed strand that ultimately reaches the cortex. This may 

 be the main reason why one finds living hyphae deeply imbedded 

 beneath several rings of wood. 



Haustoria may occasionally be found in cells of the cortex medullary 

 rays, but they are not abundant. Some of these haustoria are bi- 

 nucleated. 



There seems to be no question that Wornle was right in stating 

 that the hyphae of G. Ellisii are intercellular. 



Gymnosporangium biseptatum 



Harshberger and Wornle disagree on a second important point in 

 their studies of G. biseptatum. This relates to the presence or absence 

 of mycelium in the wood cylinder of the cedar. 



I have as yet been unable to infect the cedar with this species. 

 I have studied specimens naturally infected and especially one from a 



