CHAPTER III. 



THE PRINCIPLE OP NUMBER — Continued. 



Illustrations op Special Numbers. — It will now be advisable 

 to give examples of particular numbers occurring in flowers, 

 and attempt to account for tbem. 



One-membered Whorls. — "Where one part to a whorl is 

 only found, it may in nearly every case be regarded as a 

 degradation from some higher number. The only instances 

 I am aware of in which the calyx seems to consist of a 

 single member are some species of Aristolochia. In Musscmda 

 one out of the five sepals is greatly enlarged to become an 

 attractive organ.* 



One petal is occasionally found. Thus, four genera of 

 Vochysiacece have each only one petal to their flowers ; but 

 as the sepals are five in each of the seven genera of this 

 order, and the petals range from one to five in number, the 

 inference is clear that the solitary petal of these four genera 

 is due to the arrest of the others. 



One stamen occurs more frequently ; as in Hippuris, 

 Gentranthus, Euphorbia, Casuarina, Orchis, Ganna, Lilcea, 

 Lemna, etc. As allied genera have more than one, and it is 

 accompanied by other signs of degradation or metamorphosis, 



* If there be one external foliar organ only, it is regarded as a bract, 

 as in Willows and Aponogeton. 

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