CO-KELATION. 487 



There are certain co-relations wliicli do not appear 

 to have hitherto attracted the attention they merit ; 

 such, for instance, is that which exists between the 

 particular period at which an organ is developed 

 and its position and form. In normal morphology 

 this has, to some extent, been worked out, as in 

 the case of definite and indefinite, centrifugal and 

 centripetal inflorescences, and in the definite or in- 

 definite formation of shoots, &c. 



Other instances may be cited in the frequent co- 

 existence of regular flowers and definite inflorescence, 

 the terminal position of many peloriated flowers, the 

 relationship between indefinite inflorescence and pro- 

 longation of the axis, &c. 



Again, the simultaneous evolution of the parts of the 

 flower and their consequent verticillate arrangement, are 

 often associated with the production of different forms 

 fi'om those characteristic of organs developed in succes- 

 sion, and, in consequence, arranged spirally. In the case 

 of simultaneous development we meet with a repe- 

 tition of whorls, as in what are termed hose-in-hose 

 flowers (flores duplicati, triplicati, &c.), and also with 

 cases of peloria. In instances where the organs are 

 formed successively in spiral order, we meet with such 

 changes as median prolification, petalody, and phyllody. 

 All these are alterations which we might anticipate from 

 the activity of the growing point being checked at a 

 certain stage in the one case, while it is continuous in 

 the other. This relationship between the definite and 

 indefinite modes of growth and the form of the several 

 organs of the flower, is more constant in reahty than 

 it may appear to be from a perusal of the lists of 

 genera in the foregoing pages, in which it was not 

 possible to show sufficiently well the comparative 

 frequency of any given changes in individual plants. 

 Had it been possible to give statistics setting forth 

 the frequency of certain deviations in plants or groups 

 having a particular organisation, as compared with the 

 rarity of their occurrence in other plants of a diflcTent 



