242, PHYLLODY 
place of other organs, is frequently looked on as due 
to retrograde metamorphosis, or to an arrest of develop- 
ment. But this is not strictly correct; for mstance, 
suppose a petal, which is very generally merely the 
sheath of a leaf, with the addition of colouring matter, 
to be replaced by a perfect leaf, one in which all three 
constituent parts, sheath, stalk, and blade, are 
present, it surely can hardly be said that there has 
been any retrogression or arrest of development in the 
formation of a complete in place of an incomplete 
organ. The term retrograde here is used in a purely 
theoretical sense, and cannot be held to imply any 
actual degradation. Morphologically, as has been 
stated, the case is one of advance rather than the 
reverse, and hence the assignment of instances of this 
nature to a perversion of development, rather than to 
a diminution or to an exaltation of that process, seems 
most consistent with truth. The affected organs have 
really undergone no actual change, simply the direction 
of the organising force has been altered at a very early 
state, so that the usual differentiation of parts has not 
taken place. 
Phyllody of the bracts—As bracts are very generally 
imperfect organs, so their replacement by perfect leaves 

Fie. 126.—‘ Rose plantain,’ Plantago media var., spike contracted ; 
bracts leafy. 
