' FASCIATION AND ALLIED PHENOMENA. 



157 



Hence the base of the stem has a smaller diameter than is found 

 higher up.* 



We thus see that a fasciated stem is correlated with repeated bifurca- 

 tion of the cords (hg. 87), or what used to be called " Chorisis." This is a 

 somewhat misleading term, as it etymologically signifies " splitting," 

 whereas the elements of the cord are all present in each branch, being the 



Fig. 87. — Fibro-vascular bundles 

 cords of fasciated part. 



or Fig. 88. — Transverse section of stem of 



Lathyrus pratensis. 



result of bifurcation, and consist of a bundle of xylem united to a bundle 

 of phloem. It;is, however, a convenient term to retain. 



Simultaneously with the branching of the cords of the stem, the 

 cortical region increases so that it becomes larger ; but why the cords 

 usually increase in number in one 2)lane and not all round, so as to retain 

 a cylindrical stem, showing a circular section of cords, is not at all clear. 



Buds and Leaves. — In the normal preparation for the production of 

 leaves and their axillary buds on ordinary stems, one, three, or more cords 

 diverge at different points from the woody cylinder of the stem and enter the 

 petiole, leaving gaps in the cylinder. (Figs. 88, 89.) If there be stipules, 

 their cords always arise as branches from the most remote pair of cords 

 which enter the petiole. (Fig. 90.) 



The next cords in position to the middle one branch till they form 



Fig. 89. — Transverse section of same, 

 showing cords departing from the 

 cylinder to enter a petiole on the 

 left. 



Fig. 90.- -Transverse section of same a 

 base of petiole, showing branches 

 entering the stipules, the cylinder of 

 the axillary bud, and re-formed 

 cylinder of the stem on the right. 



more or less two semicircles. These close up and form a small cylinder 

 in order to supply the axis of the axillary bud ; while the other gaps in 

 the cylinder also close up by bifurcation of the neighbouring cord.-. 



* A specimen of Senecio Jacobcea had a fasciated stem, h inch across (long 

 diameter) at the base, and 1 inch at a point half a foot higher up ; a branch of the 

 same was ^ inch across where it issued from the main stem, and t inch at a distance 

 of 1 inch above it. A Tulip peduncle, bearing four perfect and distinct flowers on 

 long pedicels, was inch at the base, while the sum of the widths of the pedicels 



was 



16 



inch. 



