when a tendency splits up in the course of its development, each of the special tendencies
which thus arise tries to preserve and develop everything in the primitive tendency that is not compatible with the work for which it is specialized. 

this explains the fact we dwelt on in the last chapter, viz., the formation of identical complex
mechanisms on independent lines of evolution.

certain deep seated analogies between the animal and the vegetable 
have probably no other cause: the plant must have been driven by the same
impetus which impelled the animal, a primitive, original impetus, anterior 
to the separation of the two. the same may be said of the tendency of the vegetable
towards a growing complexity. 

henri bergson's creative evolution.