32 ADHESION. 



CHAPTER 11. 



ADHESION. 



Adhesion, so called, occurs either from actual union of 

 originally distinct members of different whorls or from 

 the non-occurrence of that separation which usually 

 takes place between them. It is thus in some degree a 

 graver deviation than cohesion, and is generally a con- 

 sequence of, or at least is coexistent with, more serious 

 changes ; thus if two leaves of the same whorl are 

 coherent the change is not very great, but if two leaves 

 belonging to different whorls, or two leaves in the same 

 spiral cycle are adherent, a deformation in the axis or 

 a certain amount of dislocation must almost neces- 

 sarily exist. Adhesion as a normal occurrence is 

 usually the result of a lack of separation rather than 

 of union of parts primitively separate. Instances of 

 adhesion between different organs is seen under ordi- 

 nary circumstances in the bract of the Lime tree, which 

 adheres to the peduncle, also in Ncuropeltis, while in 

 Enjthrochiton hypophyUanthu,s the cymose peduncles are 

 adherent to the under surface of the leaf. 



Adhesion between the axes of the same plant is suffi- 

 ciently treated of under the head of Cohesion, from 

 which it is in this instance impossible to make a dis- 

 tinction. Adhesion of the inflorescence is necessarily 

 a frequent accompaniment of fasciation and cohesion of 

 the branches. 



Adhesion of foliar organs may occur either between the 

 margins or between the surfaces of the affected parts ; 

 in the former case there is almost necessarily more or 

 less displacement and change of direction, such as a 

 twisting of the stem and a vertical rather than a 

 horizontal attachment of the foliar organ to it ; hence 



