DEVELOPMENT OF THE OVULE. 



175 



the bracts is much like that of the leaf ; therefore these need not 

 be specially considered here. 



491. Ovules are normally formed at definite points or lines 

 upon the ovarian wall, which answer to the edges of the carpel- 

 lary leaves. The funiculus arises as a slight elevation produced 

 by the multiplication of a cell or a group of cells under the 

 epidermis; in the centre of this elevation, and also under the 

 epidermis, further development produces a spheroidal or cone- 

 like mass, the nucleus. Then, a little later, cells at the base 

 of the nucleus begin to produce a cylinder (the inner integu- 

 ment), and shortly after, a second one is formed below and 

 outside this (the outer integument). Subsequent development 

 carries the outer integument quite up and around the inner one, 

 and the nucleus; leaving a small opening (the foramen). For 

 peculiarities in the morphology of the ovule, and for cases in 

 which one or both integuments may be wanting, see Volume I. 

 page 278. 



492. The funiculus has a collateral nbro-vascular bundle, 

 having its median plane coincident with that of the ovule. The 



bundle is surrounded by parenchyma and epidermis. It is fre- 

 quently prolonged into the integuments, being there more or less 

 branched. 



FIG. 135. Development of the ovule of Aristolochia Clematitis. A, young ovule in 

 vertical section; B, same, more advanced; tl, internal integument forming; C, a later 

 stage of same; ti, internal integument; te, external integument forming; D and E, 

 later stages of nucleus, to be described in Part II. (Warming.) 



