354 



ORGANOGRAPHY. 



Fig. 111. 



Fig. 775. Diagram of the flower of the common Wallflower. Fig. 776. 



Flower of a species of Streptanthus, with the floral envelopes removed, 

 showing a forked stamen in place of the two anterior stamens. From 

 Gray. Fig. 777. Diagram of the flower of Fumitory. 



sidered to be afforded by the flowers of many species of Hyperi- 

 cum {fig. 540) ; in these, each bundle of stamens is supposed to 

 arise from the repeated chorisis of a single stamen. Collateral 

 chorisis may be considered as analogous to a compound leaf 

 ■which is composed of two or more distinct and similar parts. 

 Transverse chorisis is supposed by Gray, and some other bota- 

 nists, to have its analogue in the ligule of Grasses {fig. 348), as 

 that appendage occupies the same position as regards the leaf, as 

 the scales of Lychnis, &c., do to the petals. 



Dr. Lindley believes that the whole theory of chorisis " is de- 

 stitute of real foundation for the following reasons : — 



" 1. There is no instance of unlining which may not be as well 

 explained by the theory of alternation. 



" 2. It is highly improbable and inconsistent with the simpli- 

 city of vegetable structure, that in the same flower the multipli- 

 cation of organs should arise from two wholly different causes ; 

 viz., alternation at one time and unlining at another. 



"3. As it is kno\\ni that in some flowers, where the law of al- 

 ternation usually obtains, the organs are occasionally placed op- 

 posite each other, it is necessary for the supporters of the unlin- 

 ing theory to assume that in such a flower a part of the organs 

 must be alternate and a part unlined, or at one time be all alter- 

 nate and at another time be all unlined, which is entirely op- 

 to probability and sound philosophy. 



" 4. The examination of the gradual development of flowers, 

 the only irrefragable proof of the real nature of final structure, 

 does not in any degree show that the supposed process of unlin- 

 ing has a real existence." 



According to Lindley's view, therefore, whenever the organs of 

 adjacent whorls are opposite to each other instead of alternate. 



