Bye ADHESION. 
CHAPTER AL 
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 
grayer deviation than cohesion, and is generally a con- 
‘sequence of, or at least 1s 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 Gap leaves in the same 
spiral. cycle are adherent, a detaemn teat in the axis or 
a certain amount of dicloeamon 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 1s seen under ordi- 
nary circumstances in the bract of the Lime tree, which 
adheres to the peduncle, also in Newropeltis, while in 
Hrythrochiton hypophyllanthus 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 
