4.S0 PKOCEEDINGS OF THE ACADEMY OF [^^Jiy, 



meets that of the unmodified stem it is much reduced in width, 

 and there are no cortical cells where, by the folding over of the 

 swelling, forceful compression occurs. The bast fibres in transverse 

 section are, as a rule, rectangular with rounded coruei-s. The lumen 

 has almost completely disappeared. In unstained mounts these 

 elements have the luster of German silver. These fibres are more 

 continuous in some places than in others. Their continuity is only 

 broken by the cortical medullary rays. 



Longitudinal sections of two swellings were studied. The swell- 

 ings used to make the sections may be described as follows : The 

 first one forms a burl-like outgrowth on one of the smaller lateral 

 branches which had grown through the activity of the fungus very 

 considerably in size, the end being rounded and clubbed. The 

 other swelling represents a malformation of the main stem and a 

 branch, a section of which is in general Y-shaped. The thicker 

 part of the swelling represents the stem of the Y. These sections 

 were stained with methyl-green. The normal tracheids are chi'omo- 

 phobic. The bordered pits are well marked in all of the tracheids. 



The plugged tracheids mentioned in the consideration of the 

 transveree sections are well marked. They stain in general of a 

 dark-green color, and the lumen seems to be enlarged and filled 

 with granular contents. The ends of such tracheids are more rounded 

 than the ends of normal ones. The cell-lumen is larger. The 

 wall is more wavy and the course of the elements more irregular. 

 In some of these plugged tracheids the contents seem to be more or 

 less granular. These become dark-gi'eeu in color by the use of the 

 methyl-green. That these longitudinally directed plugged tracheids 

 correspond to the brown spot referred to in the description of the 

 several cross-sections is easily demonstrated by observing their course 

 in the sections of lateral branches found in the longitudinal sections 

 of the swellings. It is observable that the longitudinally directed 

 tracheids filled with granular matter take a sharp bend and run 

 into the branch, Avhere they are seen in transverse section. The 

 medullary ray cells also of such sections become deeply stained 

 when methyl-green is applied. Tangential sections of the swellings 

 show the medullary ray cells stretching across the tracheids in a 

 gridiron fashion. The parenchyma cells of the medullary rays 

 are long compared to their diameter. The ratio of 5 to 1 will 

 express in an approximate manner the relative length and diame- 

 ter of such parenchyma cells. 



