II.] CONIFERS. 247 



tube, the complete elongation of which is not attained 

 until about a year after the shedding of the pollen in 

 Scotch Fir, in which the fruit is of biennial maturation. 



In Pine the embryo-sac originates in the axis of the ovule 

 as in Angiosperms, but it is usually embedded rather deeply 

 in its substance. It becomes early filled, long previous 

 to contact of the pollen-tube, with cellular tissue (an 

 endosperm) originating by free-cell-formation like the 

 endosperm of Angiosperms. Certain of these cells in 

 the embryo-sac near its upper boundary enlarge as 

 secondary embiyo-sacs (formerly called corpuscula but 

 clearly identical with the archegonia of vascular crypto- 

 gams : see pp. 256-262), within each of which, upon 

 contact of the pollen-tube, the formation of several 

 embryos is determined by the repeated division, in the 

 direction of the axis of the ovule, of a cell at the base of 

 the cavity of the secondary embryo-sac. 



Upon the number of longitudinal divisions of this 

 cell (first stage of the pro-embryo] depends the number of 

 possible embryos. Each cell resulting from this division 

 then repeatedly divides transversely, and at the same 

 time grows down into the substance of the endosperm, 

 which increases rapidly in bulk and finally displaces the 

 entire nucleus of the ovule. Of all the nascent embryos 

 contained in the same fertilized ovule but one attains 

 maturity, the rest being arrested at an early stage. As 

 the endosperm is not all absorbed during maturation, 

 the seed is albuminous. The embryo, as already pointed 

 out "in Pine, is polycotyledonous, occupying the axis of 

 the seed with an inferior radicle. 



In Cypress (Cupressus sempervtrens, an exotic species), 

 Yew (Taints baccata\ and Juniper {Juniperus communis\ 

 the Type is slightly departed from, though all agree in 

 the naked ovules of the female flowers. 



In Cypress, the scales of the male catkins bear 4 anther- 

 cells, and the ovules are numerous and erect in the axils 

 of a small number of scales arranged in a head. These 

 scales become woody and peltate, constituting a capitate 

 modification of the cone. 



In Yew, the male flowers consist of peltate scales, bear- 

 ing about 6 (3 to 8) anther-cells ; the female flowers of 

 solitary ovules, around each of which a succulent, pink- 



