486 CO-RELATION. 



position of these covds have also been considered to 

 bring about delations from the rule of alternation, 

 but in general the formation of the cords is subsequent 

 to that of the growing points or mamelons. 



Adhesions, accompanied by displacements, occa- 

 sionally produce similar deviations, the nature of 

 which is usually easily detected. 



Co-relation. The importance of this subject first pro- 

 minently brought into notice by Geoffrey St. Hilaire 

 gains in force daily. Rarely is a malformation an iso- 

 lated phenomenon, almost always it is associated, from 

 the operations of cause or effect, with some others. 

 Instances of this co-relation have been cited in the 

 preceding pages, and many more might have t)een 

 mentioned, had the consideration of the relationship 

 between form and function formed part of the plan of 

 this volume. A change in itself slight, often acquires 

 importance from its association with other alterations. 

 This is particularly well seen in the case of the recep- 

 tacle. Let an ordinarily concave thalamus remain, from 

 defective development, flat, and how great the change 

 in the appearance of the flower. Let the usually con- 

 tracted receptacle be lengthened, and the whole aspect 

 of the flowers so affected is altered to such an extent 

 that, were their history not knowTi, botanists would 

 have no hesitation in assigning them to widely separate 

 gi'oups in their schemes of classification. Peloria, too, 

 of either form, affords excellent illustrations of the 

 co-existence of one changed condition with another. 

 Not only is the form of one set of organs altered, but 

 the number, the relative proportion, and the direction 

 of the other organs of the flower are altered hkewise.^ 

 Not only is the whole symmetry changed, but the 

 physiological operations carried on in the flower un- 

 dergo corresponding alterations. 



' A singular instance of co-relation was shown by Mr. Saunders at 

 the Scientific Committee of the Royal Horticultural Society, Februaiy 

 16th, 1868, in a hyacinth with perfectly green, long, tubular, erect, not 

 honzontally spreading flowers. 



