METAMORPHOSIS 107 



VII, III), even where the phyllotaxy of the plant in gen- 

 eral is spiral. But we have in many plants a change from 

 the one arrangement to the other upon the same plant evi- 

 denced even by the ordinary foliage leaves. 



III. The parts of the flower grade into one another ; that 

 is, give evidence that they are all modifications of the same 

 kind of structures. The evidence here is of two kinds. 



1 . (a) Examine the flower of a white Water-Lily (Nymphaa) . 



Passing from the outside, the sepals are partly green 

 and partly white ; the white petals grow narrower 

 and begin to show small anthers at their tips ; the 

 white portion becomes narrower and narrower until 

 the typical stamens are found. 



(3) The Sweet-scented Shrub ( Calycanthus) shows sepals 

 gradually passing into petals, petals into stamens, 

 and stamens into pistils. It is difficult to tell in 

 some cases whether we are examining stamens 

 or pistils. 



2. In double flowers such as Roses, stamens are transformed 



into petals by cultivation, and in the double Althaea 

 (Hibiscus Syriaca) even the stigmas become petaloid ; 

 and, upon opening the ovary, the ovules are often 

 found to be changed to petal-like bodies. 



(The pupil should examine all double flowers for 

 evidence and make notes.) 



IV. Green Flowers. Occasionally Roses, Trilliums, Fig- 

 worts, Buttercups, and other flowers are found, in which some 

 or all of the floral organs are changed into green leaves. 

 Examples of such flowers are to be sought and examined. 

 This is called "reversion to a primitive condition," 



