352 OBGANOGEAPHY. 



stamens ; in this flower, therefore, -we have an addition of one 

 whorl of organs to each of the three external floral circles. In the 

 Poppy, we have a number of additional whorls of stamens {fig. 

 772). In the Magnolia family generally, the increase is chiefly 

 remarkable in the carpels [fig. 690, c). In Nymjpho'a {fig. 771), 

 the petals and stamens are greatly increased in number. In many 

 of the Eanunculacese {fig. 773), the stamens and carpels are very 

 numerous, owing to addition of whorls. As a rule, the increase 

 in the number of whorls is most common among the stamens. 

 When the increase is not excessive, the nximber of the organs so 

 increased is a multiple of the normal number of parts in each 

 whorl ; thus in the Barberry {fiig. 770), the normal number is 

 three, and that of the sepals, petals, and stamens, six, so that in 

 each of these whorls we have double the normal number. When 

 the addition of parts extends to beyond three or four whorls, 

 this correspondence in number is liable to much variation ; and 

 when the addition is very great, as in the stamens of species of 

 Clematis {fig. 773), and the carpels oi Liriodendron {fig . 590, c), 

 it cannot be well determined, in which case the symmetry is 

 disguised or destroyed ; which is also the case if the whorls are 

 crowded together. 



b. Chorisis or dcdujAication. — This is generally looked upon 

 by botanists as another means of multiplication of the parts of a 

 flower. It consists in the division or splitting of an organ in 

 the course of its development, by which two or more organs are 

 produced in the place of one. Chorisis differs from augmenta- 

 tion in the fact, that it not only increases the number of parts, 

 but also interferes with their regular alternation ; for augmen- 



Fig. 773. Fig. 774. 



Fi(j. 7T3. Diagram of tLe flower of Clematis (.EammculncecB). Fig. 774. 



Diagram of the flower of Rhamnus cathartictts. Buckthorn. 



tation does not necessarily interfere with alternation, it only ob- 

 scures it when the number of additional parts is excessive, or 

 when the whorls are crowded together. 



Chorisis may take place in two ways, either transversely, when 

 the increased parts are placed one before the other, which is 

 called ve7'tical, ixiralld, or transverse chorisis ; or collaterally, 

 when the increased parts stand side by side, which is termed 

 collatercd chorisis. Transverse chorisis is supposed to be of fre- 

 quent occurrence ; thus the petals of Lychnis {fig. 484), and 



