M. Duchartre on the Organogeny of the Malvaceae. 243 



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 immediately 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, in- 

 stead 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, sub- 

 sequently 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 m most flowers is oc- 

 cupied 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 for- 

 mation 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. We thus have ten radiant 

 series, opposed in pairs to the petals, and supported upon a com- 

 mon base, which is frequently cut into five corresponding lobes, 

 more or less marked. At a little later period, each of these tu- 

 bercles, continuing to grow more at the sides than in the median 

 line, is itself divided into two, and we find that four parallel 

 series become substituted for the two before each petal, and the 

 total number is a second time doubled. The same occurs in 

 those flowers which have very numerous stamens ; but there is a 

 slight difference in those in which they exist in less numbers. 

 Then, either fewer concentric rows arc formed, or each of these 

 rows stops at that period at which the pairs are* simple and not 

 doubled, or within the first pairs a single tubercle only is formed ; 

 this is slightly lateral and oblique, then another still more inter- 

 nal and on the opposite side, so that within the first pair we 

 find only isolated tubercles, sent off alternately, first from one 

 side, then from the other, in a zigzag direction. In all cases, 

 there are invariably five systems of stamens opposite to the petals. 



During these changes, the small common tube, to which all 

 these organs are attached, continues to elongate, raising these 



