SA O8 The Life of the Plant. DOR 3 
the leaves of Ze/inm dulbiferum and in the inflorescence of 
many species of AZ/um come under this head. 
Closely connected with metamorphosis 1s ferorza, or the 
abnormal regularity of flowers usually irregular but sym- 
metrical, z.e. so constructed that there 1s only one line by » 
which they can be divided into two similar parts. This 
phenomenon is most common. in Gramineze, Leguminose, 
Labiatee, Scrophulariaceze, and Violacez. In the common 
toadflax, Zzzarza vulgaris, for example, in which the perso- 
nate bilabiate corolla runs out into a spur, the terminal 
flower of the raceme not unfrequently’ exhibits complete _ 
peloria, ze. has a regular margin, and five spurs at equal 
distances from one another. In Composite, peloria fre- 
quently takes the form of a conversion of the ligulate into 
tubular flowers. ey 
The last class to be mentioned is the change in the ex- ~ 
ternal form of leaves, the result of an irregular accession or _ 
suppression of growth from disease. Deviations from a 
symmetry between the right and left side of the leaf occur 
normally in some plants, as the various species of Begonia | — 
[and lime], and occasionally in almost all plants. The ~ | 
relationship between the length and breadth of the leaf is 
also often disturbed. A difference frequently occurs be- — 
tween the intensity of growth of the vascular bundles and 
of the parenchymatous tissue (mesophyll) which occupies 
the space between them. When the vascular bundies grow 
more vigorously than the parenchyma, the latter is ruptured, 
and the leaves become perforated or slit, as is always the 
case in old leaves of the banana [and in some Aroidee, Fig. 
194, p. 106]. When, on the other hand, the growth of the 
parenchyma exceeds that of the vascular bundles, the leaves — 
become crumpled, as in many garden-plants, such as endive, 
parsley, &c. More rarely, outgrowths are developed on the ~ 
surface of the leaf, which themselves assume a leaf-like form.. 
In all the cases hitherto mentioned we have treated only 
of changes in form. But diseases are also caused through > 
