THE MORPHOLOGICAL COMPOSITION OF PLANTS. 35 



and more of the appearance of the sepals." The sepals, or 

 divisions of the calyx, are not unlike undeveloped leaves: 

 sometimes assuming quite the structures of leaves. In other 

 cases, they acquire partially or wholly the colours of the 

 petals as, indeed, the bracts and uppermost stem-leaves 

 occasionally do. Similarly, the petals show their alliances to 

 the foliar organs lower down on the axis, and to those higher 

 up on the axis : on the one hand, they may develop into or- 

 dinary leaves that are green and veined ; and, on the other 

 hand, as so commonly seen in double flowers, they may bear 

 anthers on their edges. All varieties of gradation into 

 neighbouring foliar organs, may be witnessed in stamsns. 

 Flattened and tinted in various degrees, they pass insensibly 

 into petals, and through them prove their homology with 

 leaves ; into which, indeed, they are transformed in flowers 

 that become wholly foliaceous. The style, too, is occasionally 

 changed into petals or into green leaflets ; and even the 

 ovules are now and then seen to take on leaf-like forms. 

 Thus we have clear evidence that in Phaenogams, all the ap- 

 pendages of the axis are homologues : they are all modified 

 leaves. 



AYolff established, and Goethe further illustrated, another 

 general law of structure in flowering plants. Each leaf 

 commonly contains in its axil, a bud, similar in structure to 

 the terminal bud This axillary bud may remain unde- 

 veloped; or it may develop into a lateral shoot like the 

 main shoot ; or it may develop into a flower. If a shoot 

 bearing lateral flowers be examined, it will be found that the 

 internode, or space which separates each leaf with its axillary 

 flower from the leaf and axillary flower above it, becomes 

 gradually less towards the upper end of the shoot. In some 

 plants, as in the fox-glove, the internodes constitute a 

 regularly-diminishing series. In other plants, the series they 

 form suddenly begins to diminish so rapidly, as to bring the 

 flowers into a short spike instance the common orchis. And 

 again, by a still more sudden dwarfing of the internodes, the 



