MORPHOLOGY. 479 
are apt to associate exclusively with one is found to 
pertain tothe other. The arrangement of the vascular 
cords in the leaf-organ finds its counterpart in the axis, 
generally, it is true, modified to suit altered circum- 
stances or diverse purposes. In some cases the dis- 
position is absolutely indistinguishable in the two 
organs. It may then be said that the distinctions 
usually drawn between axis and leaf are not absolute, 
and that, however necessary such a separation may 
be for descriptive or physiological purposes, morpho- 
logically the two organs are identical. Again, it may 
be said that leaf and axis are two phases of the same 
organ,—an organ capable of existing in its undifferen- 
tiated state in the form of a thallus among Cryptogams, 
but which in the higher groups of plants becomes 
marked out into separate portions, each portion haying 
its own distinct functions to fulfil for the common 
benefit of the whole organisation.’ 
Special morphology— Under this heading brief reference 
may be made to some of the organs whose morpho- 
logical nature has been, and still is, much contested. It 
is clear that for the due elucidation of these matters, 
development and the comparative investigation of 
similar structures in different plants must be studied. 
Teratological data by themselves can no more be 
trusted to give a correct solution of any particular 
question, than the evidence furnished by other de- 
partments of botanical science taken separately. With 
this statement by way of caution, allusion may be 
made to some of the organs whose morphological 
construction is illustrated by the facts recorded in 
the present volume. 
brought under the notice of the writer by Dr. Welwitsch recently, and 
in which some of the leaflets of the pinnate leaf of a species of Macro- 
lobium were absent, and their place supplied by flowers arranged in 
es. 
} The presence of a bud at the extremity once considered to be an 
absolute distinction between branch and leaf, which latter never forms 
a bud exactly at the apex—is invalidated by the case of the Nepaul 
barley, p. 174. 
