THE OVULES. 



109 



418 408 40T 



410 



406, Pistil of Celosia, the pericarp detached showing the young ovules. 413, Flower of Rhu- 

 barb ; pericarp removed showing the young ovule. 40T, A similar ovule (orthotropous) of 

 Polygon inn. 40S, The same, full grown ; foramen at top. 409, Section showing its two 

 coats, nucleus and sac. 410, Anatropous ovule, as of columbine; a, foramen. 411, Section of 

 same. 412, Cainpylotropous ovule, as of Bean ; a, foramen. 414, Section of a cherry, ovulo 

 anatropous, suspended. 415, Section of carpel of Ranunculus; ovule ascending. 416, Senecio; 

 ovule erect. 417, llippuris; ovule pendulous. 



533. THE NUMBER of ovules in the ovary varies from one to hun- 

 dreds. Thus in buttercups, Composite and grasses the ovule is solitary; 

 in Umbclifcrae it is also solitary in each of the two carpels; in the Pea 

 Order they are definite, being but few ; in Mullein, Poppy, indefinite^ oo), 

 too many to be readily counted. 



534. THE POSITION of the ovule in the cell is defined by certain 

 terms as follows; erect, when it grows upwards from the base of the 

 cell, as in Compositae ; ascending, when it turns upwards from its point 

 of lateral attachment; horizontal, when neither turning upwards nor 

 downwards ; pendulous, when turned downwards, and suspended, when 

 growing directly downwards from the top of the cell, as in birch. (415, 

 416,417,419). 



535. THE OVULE AT THE TIME OF FLOWERING is soft and pulpy, 

 consisting of a nucleus within two coats, supported on a stalk. The 

 stalk is called funiculus ; the point of its juncture with the base of the 

 nucleus is the ckalaza. The nucleus was first formed, then the tegmen 

 or inner coat grew up from the chalaza and covered it, and lastly the 

 outer coat, the testa, invested the whole. Both coats remain open at 

 the top by a small passage, the micropyle. 



536. CHANGE OF POSITION. In most cases the ovule, in the course 

 of its growth, changes position, curving over in various degrees upon its 

 lengthening funiculus or upon itself. When no such curvature exists, 

 and it stands straight, as in the buckwheat order, it is orthotropous. It is 



