In the vegetable world, limits of growth and life are strangely diversified. Multitudes of forms mature and perish in a few days or hours; while others, whose beginning was in a remote antiquity, have survived the habitual period of their kind, and still enjoy the luxuriance of their prime. Some species of unicellular plants are so minute that millions occur in the bulk of a cubic inch, and a flowering plant is described by Humboldt, which, when fully developed, is not more than three-tenths of an inch in height. On the other hand, we have the great Sequoia, whose mass is expressed by hundreds of tons, and specimens of the Eucalyptus, growing in the gulches of Australia, surpass in height the dome of St. Peter's...