'374 WHORLS OF CARPELS. [BOOK i. 



latter would be invariably alternate with the inner row 

 of stamens; for, if a a (fig. 124.) are the stations of five 

 stamens, b b would be the situations of the carpels : this 

 relative position is therefore considered the normal one, and 

 is in fact that which usually exists in perfectly regular flowers ; 

 but as all the parts of a flower, in consequence of the non- 

 development of some parts, or the excessive development of 

 others, are subject to deviations, either real or apparent, from 

 what is considered their normal state, it frequently happens 

 that the carpels either bear no apparent relation to the 

 stamens or are opposite to them. In papilionaceous plants, 

 for example, where only one carpel is present, it is difficult to 

 say that it bears any exact relation to the stamens, although 

 it is probable that its position is really normal with regard to 

 them ; and so also in rosaceous plants, with numerous carpels, 

 no exact relation can be proved to exist between the latter 

 and the stamens, unless it may be said to be indicated by 

 those genera, such as Spiraea, in which the carpels are reduced 

 to five ; and, finally, in such plants as Delphinium, in which 

 the carpels are three, while the floral envelopes and male 

 system are divided upon a quinary plan, it is manifest that 

 no alternation can exist between the stamens and carpels. 



As the sepals and petals most commonly consist each of a 

 single whorl of parts, so the pistil is more frequently composed 

 of one whorl of carpels than of more. There are, however, 

 certain families in which several whorls are produced one 

 within the other, as in Fragaria, Ranunculus, Magnolia, 

 Anona, and the like. In these cases it mostly happens that 

 the carpels are either entirely separate or nearly so ; but it 

 sometimes is found that syncarpous pistils are habitually pro- 

 duced with more than one whorl of carpels, and consequently 

 of cells, as in Nicotiana multivalvis, and some varieties of the 

 genus Citrus. In such instances the placentae of the outer 

 series will necessarily be applied to the backs of the inner 

 series, as has been just demonstrated. 



This mutual relation of the different rows of carpels is 

 sometimes observed when the receptacle from which they 

 arise is either convex or concave : in the former state the 

 outer series will obviously be lowermost, and in the latter 



