ORTHOTROPOUS AND CAMPYLOTROPOUS OVULES. aol 
being straight as in the above instance, becomes more or less 
curved, or even altogether inverted. Thus in the Wallflower 
(fig. 744), and other plants of the order to which it belongs, as 
well as in the Caryophyllacez and many other plants, the apex 
of the ovule becomes gradually turned downwards towards its 
base, and is ultimately placed close to it, so that the whole 
Fic. 743. ; Fic. 744. 
cK “Aue 
Fig. 743. Vertical section of the orthotropous ovule of Polygonum. ch. 
Chalaza. prim. Primine. sec. Secundine. mv. Nucellus. s. Embryo-sac. 
m. Micropyle.——Fig. 744. Vertical section of a campylotropous oyule 
of Wallflower (Cheiranthus). jf. Funiculus. ch. Chalaza. d. Primine. s. 
Secundine. 7. Nucellus. mic. Micropyle. . 
ovule is bent upon itself, and a line drawn from the micropyle, 
mic, through the axis of the nucellus, m, and its coats, would 
describe a curve ; hence such ovules are called campylotropous or 
curved. In these ovules, the chalaza, ch, and hilum correspond 
as in orthotropous ones, but the micropyle, mic, instead of being 
at the geometrical apex of the ovule, is brought down close to 
Fia. 740. 
Fig. 745. The campylotropous ovule of the Mallow in its different stages of 
development. From Le Maout. In @ the curvature is commencing, in } 
it is more evident, in ¢ stil! more marked, and in d it is completed. /. 
Funiculus. p. Primine. s. Secundine. m. End of nucellus. ev, Exostome. 
end. Endostome. 
the hilum or base. The progressive development of the campylo- 
tropous ovule is well seen in the Mallow, as represented in figure 
745, a, b,c, d. This kind of ovule appears to be formed by one 
side developing more extensively than the other, by which the 
micropyle is pushed round to the base. 
In a third class of ovules the relative positions of parts is 
