MORPHOLOGY. 479 



are apt to associate exclusively with one is found to 

 pertain to the 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 having 

 its own distinct functions to fulfil for the common 

 benefit of the whole organisation.^ 



Special morpliology. 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 i-ecently, and 

 in which some of the leaflets of the pinnate leaf of a species of Maci-o- 

 lobiwn were absent, and their place supplied by flowers arranged in 

 cymes. 



' The presence of a bud at the extremity once considered to bo an 

 absolute distinction between branch and leaf, which latter never f<.)rms 

 a bud exactly at the apex is invalidated by the case of the Nepaul 

 barley, p. 174. 



