C1IOHISIS Oil DKfoL'PLICATIOK. 



213 



454. CllOl'isis or Dcilliplication. Tlie name dedonblement of Dunal, 

 which has been translated dediiplication, literally means unlimng ; 

 the original hypothesis being, that the organs in question imline, or 

 tend to separate into two or more layers, each having the same 

 structure. We may employ the word deduplication, in the sense 

 of the doubling or multiplication of the number of parts, without 

 adopting this hypothesis as *o the nature of the process, which at 

 best can well apply only to some special cases. The word chorisis 

 (xaipttm, the act or state of separation or multiplication), also pro- 

 posed by Dunal, does not involve any such assumption, and is ac- 

 cordingly to be preferred. By regular multiplication, therefore, we 

 mean the augmentation of the numbe? of organs through the de- 

 velopment of additional circles ; which ^oes not alter the symmetry 

 of the flower. By chorisis we denote the production of two or more 

 organs in the place of one, in a maimer analogous to the division of 

 the blade of a leaf into a number of separate blades, or leaflets. 



455. Chorisis, or the division of an organ into a 367 

 pair or a cluster, may take place in two ways. 

 In one case the parts or organs thus produced 

 stand one before the other ; in the other case they 

 stand side by side. The first is named transverse 

 chorisis ; the second, collateral e/iorisis. Both 

 must evidently disturb or disguise the normal 

 symmetry of the blossom. 



456. Collateral Chorisis is that in respect to 



which there is least doubt as to the nature of the 



process. We have a good example of it in the 



te.tradynamous stamens (519) of the Mustard or 



Cress family (Fig. 406). Here, in a flower with 



a symmetrical tetramerous calyx and corolla, we 



have six stamens ; of which the two lateral or 



shorter ones are alternate with the adjacent 



petals, as they normally should be, while the four 



are in two pairs, one pair before each remaining interval of the 



petals ; as is shown in the annexed diagram (Fig. 367). That is,. 



on the anterior and on the posterior side of the flower we have two 



stamens where there normally should be but a single one, and where, 



FIG. 357 Diagram of a (tetradynamous) flower of the order Cruciferoe. 

 FIG. 303. Flower of Streptanthus bjacintlioidcs, from Texas (the sepals and stamens re- 

 moved), showing a forked or double stamen in place of the anterior pair. 



