M. Duchartre on the Organogeny of the Malvacee. 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. Hach 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 in 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 mto 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 
shght difference in those in which they exist im less numbers. 
Then, either fewer concentric rows are 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 
