PROGRESSIVE METAMORPHOSES. 



293 



that stamens can undergo in tbis' direction is to be more 

 or less converted into pistillarj structures. This is by no 

 means uncommon. Either the filament alone, or the anther 

 alone, or both together may be affected. The reader is 



Fig. 73. — Aquilegia, with poUeniferous spurs 

 (after W. G. Smitli). 



Fig. 74. — Ovuliferous petals, etc. , 

 of Begonia (after Masters). 



referred to Dr. Masters's Teratology for a description, with 

 figures of several kinds.* It is more usual for the filament 

 to become enlarged into the ovarian part bearing rudimentary 

 ovules ; but when the anther is involved, it may be partially 

 or wholly transformed. In these cases the connective is 

 usually prolonged into a stigmatiferous process, f As an 

 example often described is that of the Houseleek, in which 

 the margins of the anther cells become ovuliferous in various 

 degrees ; as in Fig. 75, where ovules are borne by the pos- 

 terior sides only, instead of pollen. In other cases the 

 filament bears rudimentary ovules as well. Dr. Masters 

 points out that " where there is a combination of the 



* Page 303. 



t In Aristolochia this change seems to be permanent and functional. 

 See above, p. 83. 



