74 HISTORY OF PHYSIOLOGY. 



all doubt. And thus the snap-dragon, of which we have spoken 

 above, is derived from the Peloria, which is the normal condition of 

 the flower, by the abortion of one stamen, and the degeneration ot 

 two others. Such examples are too numerous to need to be dwelt on. 



Sect. 2. Application of Vegetable Morphology. 



THE doctrine, being thus fully established, has been applied to solve 

 different problems in botany ; for instance, to explain the structure of 

 flowers which appear at first sight to deviate widely from the usual 

 forms of the vegetable world. We have an instance of such an appli- 

 cation in Mr. Robert Brown's explanation of the real structure of vari 

 ous plants which had been entirely misunderstood : as, for example, 

 the genus Euphorbia. In this plant he showed that what had been 

 held to be a jointed filament, was a pedicel with a filament above it, 

 the intermediate corolla having evanesced. In Orchidece (the orchis 

 tribe), he showed that the peculiar structure of the plant arose from 

 its having six stamens (two sets of three each), of which five are 

 usually abortive. In Coniferce (the cone-bearing trees), it was made 

 to appear that the seed was naked, while the accompanying appen- 

 dage, corresponding to a seed-vessel, assumed all forms, from a com- 

 plete leaf to a mere scale. In like manner it was proved that the 

 pappus, or down of composite plants (as thistles), is a transformed 

 calyx. 



Along with this successful application of a profound principle, it 

 was natural that other botanists should make similar attempts. Thus 

 Mr. Lindley was led to take a view 11 of the structure of Reseda 

 (mignonette) different from .that usually entertained ; which, when 

 published, attracted a good deal of attention, and gained some con- 

 verts among the botanists of Germany and France. But in 1833, Mr. 

 Lindley says, with great candor, " Lately, Professor Henslow has satis- 

 factorily proved, in part by the aid of a monstrosity in the common 

 Mignonette, in part by a severe application of morphological rules, 

 that my hypothesis must necessarily be false." Such an agreement 

 of different botanists respecting the consequences of morphological 

 rules, proves the reality and universality of the rules. 



We find, therefore, that A principle which we may call the Princi- 

 ple of Developed and Metamorphosed Symmetry, is firmly established 



11 Lindley, Brit. Assoc. Report, iii. 50. 



