A study in the Morphology of the Leaf. 251 
be in accordance with our treatment of the shoot as a whole, 
is applicable to the most difficult cases. It is obviously an 
elastic method, and in this respect it accords with the morpho- 
logical spirit of the time; it is generally recognised that in 
their adaptation to special physiological requirements plants 
are susceptible of the most varied development, and that this 
does not follow a rigid type. This is admitted as regards the 
arrangement of leaves on the shoot, in the branching of the 
shoot, and in the development of the nodes and internodes. 
It is time that, in considering the leaf, which is the most 
plastic of all members, a similar elasticity of method should be 
adopted, and the assumption that in complicated leaves the 
parts are . necessarily referable to sheath, petiole, and lamina 
should be recognised as being based on insecure foundations. 
December , 1888 . 
