METAMORPHOSIS. 



173 



logous, that, for example, the lamina may merge into 

 the petiole to form a wholly undifferentiated leaf 

 like that of many Monocotyledons, it is known that 

 the 4-laminar or -winged anther-structure may occur, 

 in a semi-petaloid stamen, on the filament and there 

 only, either at its base or throughout its length ; 

 or both filament and anther may be similarly con- 



Fio. 129. — Tulipa Gesneriana (Garden Tulip). The six stamens of a 

 flower which have all become partially petaloid. 



structed in this way. Bach wing corresponds to an 

 anther-loculus, much the same retrogressive changes 

 occurring in petaloid as in leafy stamens. Sometimes, 

 however, as in Rhododendron, the four wings are 

 present while there occur two complete anthers in the 

 central median position; this may be accounted for 

 by assuming that incipient lobing is .taking place, and 

 in each lobe, as in the main leaf, anther-formation 



