ESSENTIAL ORGANS. THE OVULE. 



227 



466. In general however, changes take place on the ovule, so that it 

 deviates from the straight line. Thus it may be curved upon itself, so 

 that the foramen approaches to the hilum or placenta, and ultimately is 

 placed close to it, while the chalaza is only slightly removed from the 

 hilum. This change depends apparently on the ovule increasing more on 

 one side than on the other, and as it were drawing the chalaza slightly 

 to one side of the hilum opposite to that where the foramen is applied. 

 Such ovules are called campylotropal or campylotropous (x.aft.'jrfaog, 

 curved), when the portions on either side of the line of curvation are 

 unequal (fig. 419) ; or camptotropal (KX^^TOS, curved), when they are 



equal (fig. 420). Curved ovules are found in Leguminoste, Cruciferas, 

 and Caryophyllaceae. The union between the parts of the curved por- 

 tion usually becomes complete, but in some cases there is no union, 

 and the ovules are lecotropal, or horse-shoe shaped (>,kx.og, a hollow 

 disk, and TgoVoj, mode or form). 



467. When in consequence of the increase on one side, the ovule is 

 so changed that its apex or foramen (fig. 421, 4, n,) is in close apposition 



Fig. 419. Campylotropal or Campylotropous ovule of the Stock. 1. Ovule entire. 2. Ovule 

 cut lengthwise. /, Funiculus or umbilical cord, c, Chalaza, n, Nucleus, te, Primine or outer 

 covering, ti, Secundine or inner covering, ex, Exostome. eel, Endostome. 



Fig. 420. Carpel of Menispermum canadense, with a curved or camptotropal ovule, o. f, 

 Funiculus. s, The base of the style. 



Fig. 4-21. Ovule of Chelidonium majus at different stages of development, h, Hilum or um - 

 bilicus. ch, Chalaza, /, Funiculus or umbilical cord, r, Raphe. n, Nucleus, ti, Secundine. 

 te, Primine. ed, Endostome. ex, Exostome. 1. First stage: nucleus still naked. 2. Second 

 stage: nucleus covered at its base by the secundine. 3. Third stage: the primine developed 

 and covering the secundine at its base. 4. Fourth stage : the ovule completely reflected, and 

 its point turned downwards. 5. The same cut longitudinally, to show the relation of its different 

 parts. 



