Linnæus adopted from Cæsalpinus the opinion that the Calyx proceeded from the bark, like the leaves, because of its similarity in colour and texture to those organs. He even refined upon the original idea, and supposed this part to proceed from the outer bark, while the more delicate corolla originated in the liber. What is now known of the physiology of the bark, as explained in several of our preceding chapters, renders this hypothesis totally inadmissible.
The knowledge of the real use of leaves, see chapter 16, may however throw some light upon that of the calyx. Besides protection of the flower from external injuries, which is one evident use of this part, it appears highly probable that it may often contribute to the growth and strength of the stalk which supports it, as the leaves do to that portion of the branch below them. The stalk often swells considerably during the growth of the flower, especially just below the calyx, becoming more woody, an alteration frequently necessary for the support of the ripening fruit. When the calyx falls very early, as in the
