Really inspirational, as there is a lot of both variation and repitition in nature, the possible avenues of development or investigation is rather large. I've got a couple of books in the library related to the crossover - currently unread is "Curves of Life" (unavailable at Amz now, whilst Elams book Geometry of Design: Studies in Proportion and Composition
btw, the amazon search widget needs some serious speed help, no wonder there is a separate "optimize" selection in the info - @blogger