CELLULAR CONSTRUCTION 



[CH. 



(Fig. 109, B). The median line seen in Todea may very probably coincide 

 with the limit of the two rows of segments which form the wing. 



In the roots of the Osmundaceae, which are commonly more massive 

 than those of the Leptosporangiate Ferns, a single conical initial cell is 

 frequently found. But often there may be a plurality of them, two, three, 

 or four: and their form is sometimes obconical, sometimes with transversely 



Fig. 109. Vertical sections through the massive wings of the leaves of Aiigiopferis (left) 

 and oi Todea barhara (right). 



Fig. 1 10. ^ = median longitudinal section through the root-tip of Osniuiida regalis showing two trun- 

 cated initials (X), segments being cut off from both ends, as well as from the sides. ( x ^oo.) 

 (Compare Schwendener, Sitz. k. Pretiss. akad. 1882, Pt. vil, Fig. i ol Angiopteris.) ^ = transverse 

 section through the root-tip of Todca barbara, showing four initials (X), and the principal walls 



(P,P). (X200.) 



truncated apices (Fig. no, A and B). Such conditions, which usually show 

 irregularities of segmentation, have been observed both in Osmunda and 

 Todea. Perhaps the most enlightening of them all is the state seen in 

 certain of their roots where there are three initials (Fig. ill, A and B). 

 These are separated by walls readily recognised as corresponding to the 

 principal walls of Fig. 102, while walls corresponding to the sextant walls (s) 

 also traverse the apical group itself. It thus appears that the gap in the 



