MOEPHOLOGY OF MALLOWS. 71 



by Duchartre. The calyx, which at a later period becomes 

 monophyllous with five divisions, appears at first in the form 

 of a continuous rim, surrounding the central mass of the 

 flower, bounded by a large convex tubercle having no distinc- 

 tion of parts. This border soon sends off five small festoons, 

 which correspond to the five sepals thus united at the base 

 from the commencement. This mode of formation is found 

 in the envelopes of all those flowers having a monophyllous 

 calyx or corolla, the development of which the author has 

 had an opportunity of studying. The petals and stamens 

 may be subsequently distinguished and are simultaneously 

 developed, so that it is well to trace their evolutions together. 

 Soon after the appearance of the calyx, the margin of the 

 central tubercle becomes raised into five smaller tubercles, 

 which are rounded, alternating with the segments of the 

 calyx, and thus representing the floral whorl which imme- 

 diately succeeds it. Each of these tubercles soon appears 

 like two in juxtaposition, its development ensuing more 

 rapidly at the two sides than in the median line : and thus, 

 instead of five small primitive eminences, we have five pairs. 

 Nearly at the same time a slight transverse fold appears 

 below and outside of each of these five projections ; this 

 appears to be another appendage of the tubercle, which, at 

 first single, subsequently becomes double. The fold becomes 

 the petal ; the tubercles become stamens. Hence the petals 

 and stamens here belong to one and the same group of organs 

 developed from a base which is common to that spot which 

 in most flowers is occupied by the petal alone. 



The petal in its further development, which is generally 

 rather slow, much more so than that of the stamens, does not 

 become doubled, and gives no other indication of this tendency 

 except in its more or less bilobate summit. 



Not so, however, with the stamens ; for shortly after the 

 first ten staminal tubercles have become distinct, we find that 

 a formation perfectly similar to the first is produced. Five 

 new pairs of tubercles opposite to the first, appear in a more 

 internal circle ; then a third arranged concentrically, and 

 consisting of ten other tubercles ; then a fourth, so that the 

 total number is successively doubled, tripled, and quadrupled. 



