climbing in the genus Calamus. 1 3 1 
and the leaf to which it is adherent is about §, so that for all 
practical purposes the two are nearly opposite. If then the 
shoot of Calamus in straggling over other plants comes to 
rest in a forked branch, these opposite outgrowths would 
catch upon the fork, and serve as a support, just as in various 
plants divaricating branches ( Lantana , Pisonia , etc.) or thorns 
( Carissa ) serve the same end. Thus the displacement of the 
axillary bud is in this case to be regarded as an adaptation of 
the development of the shoot to meet the immediate needs of 
the plant. 
Finally, the two sections of the genus show two very dis- 
tinct types of adaptation of the shoot to meet the exigencies 
of a climbing habit : the one developes the apex of the leaf, 
the other the axillary bud as a flagellum/ Thus we see once 
again how plastic is the vegetative shoot in its mode of de- 
velopment within a single genus ; or, in other words, how 
variable within a narrow circle of affinity may be the localisa- 
tion of intercalary growth in shoots which correspond closely 
to one another in the origin and primary arrangement of the 
constituent parts. 
