96 ALTERATION OF POSITION. 
central axis of the flower, after the fashion of a spiral 
tube.’ 
Displacement of the carpels arises from one or other of 
the causes above alluded to, and when suppression 
takes place in this whorl it generally happens that the 
place of the suppressed organ is occupied by one of 
the remaining ones, which thus becomes partially dis- 
located. 
Displacement of the placentas aud ovules is a necessary 
result of many of the changes to which the carpels are 
subject. The disjunction or dialysis of the carpels, for 
instance, frequently renders axile placentation mar- 
ginal. Moreover, it frequently happens, when the 
carpels become foliaceous and their margins are discon- 
nected, that the ovules, in place of bemg placed on the 
suture, or rather on the margins of the altered carpel, 
are placed on the surface of the expanded carpel. 
Thus, in some double flowers of Ranunculus Ficaria that 
came under the writer’s notice the carpels were open, 
i.e. disunited at the margins, and each bore two im- 
perfect ovules upon its inner surface a little way above 
the base, and midway between the edges of the carpel 
and the midrib, the ovules being partly enclosed within 
a little depression or pouch, similar to the pit on the 
petals. On closer examination the ovules were found 
to spring from the two lateral divisions of the midrib, 
the vascular cords of which were prolonged under the 
form of barred or spiral fusiform tubes into the outer 
coating of the ovule. In this instance, then, the ovules 
did not originate from the margins of the leaf, nor 
from a prolonged axis, but they seemed to spring, in 
the guise of little buds, from the inner surface of the 
carpellary leaf.’ 
The occurrence, also, of different forms of placen- 
' See also Schlechtendal, ‘ Bot. Zeit.,’ iv, p, 804. Primula veris, parti- 
bus perigonii spire in modum confluentibus. 
= Seemann’s ‘ Journal of Botany,’ vol. v, 1867, p. 158. 
