POSITIVE DEDOUBLEMENT. 



07 



calyx of Cruciferae and CapparidaceaB, the outermost 

 corolla-whorl of the Papaveraceous type (from which 

 the Crucifeme, etc., have been derived) became trans- 

 formed into sepals, the four diagonally-placed petals in 

 Cruciferaa and Capparidaceas could only, as Celakovsky 

 states, have been obtained by positive dedoublement of 

 the two medianly-placed petals of the remaining (inner) 

 whorl, and not by transformation of stamens. If this 

 is so, then in the evolution of the Cruciferous flower 

 we see an interesting admixture both of reduction and 

 multiplication. 



Fig. 86. — EscJischoltzia. Diagram of outer corolla-whorl of two (p l ), 

 and inner corolla- whorl of four petals (jr). (Cf. Crucifera?.) 

 (After Benecke.) 



Now, Benecke describes, as an abnormality, a pre- 

 cisely similar formation of four diagonally-placed 

 petals by positive dedoublement of the two petals of 

 the inner corolla-whorl (fig. 86). But this was in the 

 Papaveraceous genus Eschscholtzia, in which, of course, 

 there is also present an outer whorl of two transverse 

 petals. So that here we have occurring in actualit} 7 

 the same phenomenon in the very order in which it 

 was theoretically postulated by Celakovsky in order to 

 account for the origin of the corolla of Crucifera?, etc. 



In Veronica the large posterior median petal, the 

 result of the fusion of two, reverts sometimes to the 



