88 HOEPHOLOGY, OE COMPAEATIYE ANATOMY. 



White Clover with more or fewer of the organs modified in this way, the 

 pistil, one or more of the stamens, &c. appearing- in the form of green 

 leaves, occasionally compound and ternate, as on the stem below. In the 

 Double Cherry of gardens, the place of the pistil is often occupied by a 

 pair of green leaves ; in the Fraxinella a circle of green leaves has been 

 observed in the place of the ovary. 



Substitution and Metamorphoses. Almost all polypetalous flowers, 

 and many gamopetalous, are capable of being " doubled by cultivation, 

 that is to say, the number of petals maybe increased at the expense of the 

 stamens, or of these and the pistils. For example, the Wild Rose has 

 bat live petals, and many stamens and pistils, but in our garden Roses 

 the numerous stamens and pistils are often altogether replaced by petals. 

 In many cases intermediately formed structures exist in such double 

 flowers : in the double early Tulip, for example, we almost always find 

 monstrous organs, half-petal and half-stamen, and even half-stamen and 

 half-carpel ; the same may be observed in double Pinks and Carnations. 

 The ovules have been seen bearing pollen, while it is frequent to find the 

 stamens bearing ovules. Illustrations obtained in this way might be 

 multiplied ad itifinitum. It should be observed, however, that in double 

 flowers we frequently find not only all the essential organs replaced by 

 petals, but an actual multiplication of the natural number of organs, as in 

 Roses, Camellias, double Daffodils, &c. 



Prolification, In the last place, we may advert to the phenomena of 

 the abnormal evolution of buds within the limits of flowers. Cultivated 

 Roses sometimes send out a leafy shoot from the centre (prolification), 

 the terminal bud not becoming arrested as is natural; on Apples and 

 Pears we occasionally see one or two leaves growing out from the 

 summit, from the same cause. In addition to this, the organs of the 

 flower may assert their foliar nature by producing flower-buds in their 

 axils, like stem-leaves. This has been observed in the case of the petals 

 of Celastrus scandens, and also of Clarkia elegans, and occurs sometimes 

 in garden Roses*. 



These general observations will serve to show the essential homology of 

 all the lateral organs of flowering plants with ordinary leaves, and more 

 especially with the vaginal or leaf-scale portion of the leaves. The laws 

 under which varieties of form &c. are produced within the limits of the 

 flower all substantiate the same general principles. 



Parts of the Flower. The parts of flowers are : the perianth, 

 consisting of (1) the sepals, forming the calyx, (2) the petals, forming 

 the corolla, and enclosing (3) the stamens, forming the androecium, 

 and (4) the carpels, forming the pistil orgyncecium. That portion of the 

 peduncle from which all these organs spring is called the receptacle or 

 thalamus; it seldom, has the internodes much developed, but is more 

 or less expanded horizontally. It is sometimes convex or conical and 

 elongated, and sometimes concave. AVhen it forms a flattened 



* A general review of these abnormal or unusual formations, and of the 

 inferences that may be derived from them, is given in Dr. Masters' ' Vegetable 

 Teratology,' published by the Eay Society. 



