160 



COMPOUND ORGANS OF PLANTS. 



hilum is not seen at s, the part where the raphe joins the 

 chalaza, but at h, the part where it unites with the placenta. 



These three forms of ovules are by no means clearly defined 

 in nature, but exhibit varieties, among which we must mention 

 the amphitropous or heterotropous ovule, which is produced by 

 a partial adhesion of the funiculus or raphe to the ovule, 

 (Fig. 63.) The funiculus is seen at right angles to the ovule, 

 and the hilum is placed midway between the micropyle and 

 chalaza. The Leguminosse or pea tribe have generally ovules 

 of this character. 



Anatropous ovules are the most common in plants. The 

 orthotropous form is considered to be the condition of all ovules 

 at the commencement of their development, and the other 

 forms are referable to changes produced during growth. The 

 anatropous ovule of the celandine and the campulitropous ovule 

 of the mallow, have been traced from the orthotropous condi- 

 tion at the commencement of their growth, through all the 

 intermediate stages of development. 



Fig. 63. 



Fig. 64, is a representation of the development of the anatropous ovule of the 

 Celandine, (Chelidonium majus.) 1. and 2, are the first stages. The primine and secun- 

 dine investments are marked p and , and the summit of the nucleus n. 3 is the fully 

 developed ovule after it has executed its demi-revolution on its funiculus/. The 

 reason of this singular change in the position of the ovule will appear in the next 

 chapter. 



All these changes* in the structure, form and position of the 

 ovules, are executed whilst the flower buds are forming. About 



