90 ALTERATION OF POSITION. 
the extremity of the axis, a position which, under 
ordinary circumstances, no leaf could assume. The 
explanation given by the Belgian professor is, that the 
axis in this case, instead of throwing off a pair of leaves, 
one on each side, had from some cause or another 
produced only one; this one not only being much 
larger than ordinary, but brightly coloured, thus 
assuming some of the characteristics as well as the 
position of the inflorescence. 
Alterations in the usual arrangement of leaves, how- 
ever, are not always dependent on or coexistent with 
other teratological changes, but may simply depend on 
a natural elongation of the internodes, or on fission or 
multiplication ; for mstance, in some conifers, such as 
the Larch, (Abies Larix) or Pinus pinea, there may be 
found at different stages in the growth of the branches 
leaves in crowded fascicles or tufts; while, when 
erowth is more rapid, the leaves may be disposed in 
a spiral or alternate manner. 
In the yew (Taaus) the leaves at the ends of the 
shoots not unfrequently lose their usual distichous 
arrangement and become arranged in a close spiral 

Fia. 42.— Altered arrangement of leaves of yew, Tawus baccata. 
manner, the elongation of the shoot being arrested. 
This appears to be the result of the injury effected by 
some insect. 
