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 and 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 being 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 Bammculus Flcaria 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 httle 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 Sohlechtendal, ' Bot. Zeit.,' iv, p, SO-t. Primula veris, parti- 

 bus perigonii spirce in modum confiuentibu^. 

 ' Seemann's ' Journal of Botany,' vol. v. 1867. p. 158. 



