1915 Kibbe; on Alaria 45 



the stipcj parallel with the plane of the lamina. In the center of this 

 area are many sieve-tubes, but towards the extremities of this area there 

 are so many sieve-tubes that only enough space is left between them 

 for the hyphal chains of the pith web. 



The sieve-tubes of the stipe do not have greatly elongated cells 

 (Fig. 1), owing to the fact that the stipe is never long. Fifteen stipes 

 were measured, and their average length was found to be only 8.54 cm. 

 Since it grows so little during the life of the plant, the inner cells do 

 not need to stretch greatly because of the rapid growth of the cortical 

 cells. The cortical cells are occasionally drawn out of proper align- 

 ment, however, thus forming clefts or rifts in the pith tissue. The upper 

 portion of the stipe (Fig. 2), and the rachis (Fig. 3), show increasingly 

 larger rifts, which tend to run more nearly longitudinally in the pith 

 cylinder as the base of the lamina is approached. The rachis has 

 longer sieve-tubes, but some of the chains of cells are found to be 

 breaking down. 



In cross-section (Fig. 10) these rifts run roughly parallel to the long 

 diameter of the pith area. The size of the rifts is greater in the pith 

 of the rachis than in that of the stipe. They are found at any point 

 throughout the central region of the pith, and look like slits torn in 

 the tissues by a force applied at right angles to the long diameter of 

 the pith area. The cells lying along the sides of the pith area have 

 become elongated in the direction of the long diameter of this area, 

 and are very narrow. Their appearance indicates that they have been 

 subjected to some strain in that general direction. The ragged appear- 

 ance of the rifts further suggests strain. 



In the lower lamina the pith is freely rifted (Fig 4). Patches of 

 fairly compact hyphae lie between these rifts. The hyphal cells are 

 larger, but no more numerous than they were in the stipe and the rachis. 

 The central, or true pith area, broadens as the rifts in the septa increase 

 in size. 



The first true chamber in the entire plant examined was 20.6 cm. 

 from the base of the lamina. This chamber did not arise as a new 

 feature in the plant structure. Before its appearance, long, ragged 

 slits appeared along the medium line of the longitudinal sections. In- 

 stead of many small rifts, there is a tendency to form one large one. A 

 long jagged rift appears along the median line of the longitudinal sec- 

 tion, while large masses of hyphal chains form poorly organized septa 

 between rifts. Small clefts are found in this septum-like mass. The 

 walls along the sides of the large longitudinal rift bulge outward slightly, 

 as if they had by bulging torn the hyphal chains asunder, to form rifts. 

 Only a few broken fragments of chains of sieve-tube cells now appear, 



