ATROPHY OF ORGANS FROM LACK OF USE 263 



superior glumes remain ; the inferior, pressed against 

 the axis, disappear after the embryonic develop- 

 ment of the flower. 



3. Degeneration of palece and of stamens. Lack 

 of space is probably the immediate cause of the 

 disappearance of palese in the receptacles of some 

 composite flowers and of the posterior stamen in 

 the flowers of some Scrophulariaceae and Labiates. 



In normal racemose inflorescences each floret 

 grows in the axil of a reduced leaf called a 

 bract. When the axis of the inflorescence is 

 shortened and the florets crowded, as in the 

 capitula of composite flowers, it frequently hap- 

 pens that the bracts of the florets (termed 

 palese) disappear. This absence is most usual 

 when the capitulum is small and the florets are 

 large. 



In Labiates and most Scrophulariacese, although 

 the ancestral number of stamens was five, there are 

 not more than four present ; when only one is 

 absent, it is the original posterior stamen which 

 was pressed against the axis of the inflorescence. 



2. Atrophy from lack of use. 

 1. FUNCTIONAL INUTILITY. 



(1) Etiolated plants and immobile limbs. We 

 have already quoted as instances of accidental 

 atrophy, cases of degeneration of leaves in etio- 



