1914] 



BR A NNON—FA SCI A TION 



519 



prominent 



axis of the young plant. Fig. 2 shows the relative size and the 

 shape of the cortex ridges and also the flattened xylem and pith 

 in a transverse section of modified cottonwood stem. This section 



Fig. 2. — Transverse section of a fasciated cottonwood stem one year old: X8; 

 the notable cortex ridges and change of symmetry in the cross-section of the stem 

 are well illustrated by these sections. 



shows that pith, xylem, phloem, and cortex maintain the same 

 relative positions in 



specimens 



normal cottonwood stem. The two exaggerated features of 

 these flattened stems are the huge cortex ridges and the modi- 

 fication of radial symmetry. 



