438 



FERTILIZATION AND FORMATION OF FRUIT IN PHANEROGAMS. 



In the Silver Fir, Spruce Fir, Pine, and other Conifers, comprised under the 

 family Abietineae, the nucleus of the egg-cell divides into four at the base of the 

 egg-cell, and here four little cells are produced, arranged like a rosette at that end. 

 Each of these is divided into three stories, and the four cells forming the middle 

 story elongate, diverge, and grow down into the endosperm, carrying the little 

 embryonal cells at their tips. The four cells of the upper story remain attached to 

 the residue of the egg-cell, and serve as a fulcrum for the elongating tubes — the 

 suspensors. As in the Gnetacere, the embryonal cells become modified into embryos, 



Fig. 332,— Branch of the Bread-fruit Tree (Artocarpus incisa) showing a male inflorescence (sausage-shaped, to the right), s 

 female inflorescence (globular, near the apex) and a collective fruit (to the left). (After Baillon.) 



but ultimately only one of them prevails, and, growing at the expense of the food- 

 material, is a conspicuous object in the ripe seed (fig. 335^). A portion of the 

 endosperm remains as a mantle around the embryo, and is only absorbed at ger- 

 mination. 



In the Juniper, Arbor Vitse (Thuja), Cypress, and other Conifers belonging to 

 the family Cupressinese, each egg-cell, after fertilization, gives rise to but a single 

 embryo (though there are exceptions to this rule). Otherwise the events are not 

 very different from those occurring in the Abietinese. 



The Integument of the ovule in Gymnosperms forms the seed-envelope (or testa), 

 as in Angiosperms. The Micropyle becomes closed up, and the whole testa very 

 hard. In the Pines, Firs, &c. (Abietineae), the micropyle points away from the free 

 margin of the open scale which bears the ovules (fig. 335 ^ ), i.e. towards the axis of 



