418 lUSiniLlZATlON AND roUMATION OF FHOri' tN PHANISUOGAMS. 



fuller knowlodge of the dot.(vils will be obtained is exceedingly probable, ia view of 

 til© active state of reseai'ch into tliese processes. 



In the Qymnoi^pcnm, the group of Flowering Plants with exposed ovules, 

 though the essential fuels of fertilization— the fusion of the male sexual cell with 

 the female sexual cell (egg) — are the same as in the ^iif/wspei'Mis, just described, 

 in many suboixUnnte points they exhibit marked dill'erenoes. The male flowew of 

 Qymnosperms produce stamens with antliers in which pollen-grains are developed 

 much as in Angiosperms. The aiTaugements, howevei', associated with the produc- 

 tion of ovules ai'6 simplei' than in the Angiosperms, and recall to some extent the 

 characters presented by certain Ferns, In the Ferns and other Cryptogams it will 

 be remembered that fertili/,ation is under water, whilst in Phanerogams this ia 

 accomplished through the medium of the air (e/, p, 71), The spermatoeoids of the 

 Cryptogams roach the egg-cell in the oogonium or archegonium by swimming; they 

 ai'e naked protoplasmic mosses, and need no enveloping and protective cell-wall, It 

 is otherwise in the Phanerogams, whero atrial fei'tiliaation obtains. Here a mem- 

 brane around the spermatoplasm is of great value; it serves to protect the contents 

 of the pollen-grain during its journey through the air, and afterwards, in comieotion 

 with the pollen-tube, is of the utmost value in conveying the male sexual cell to the 

 egg. Notwithstanding tlie reseniblance presented by the female flowers of many 

 Qymnosperms to certain Cryptogams, they agree with the Angiosperms in tlie fact 

 that the male cell is brouglit to the egg-cell by means of a pollen-tube, In this 

 point all Qymnosperms agree, is. the Cycads, Conifers, and Qnetaoom. 



The ovules of Gyninospernis show the grosser characters of those of Angiosperms, 

 In fig. 886 ' is shown a scale from a female flower (cone) of the Scotdi Pine (Pinws 

 sylveatns). Right and left at its base are the ovules, two in number. Eaoli ovule 

 exhibits a central nucellus and a conspicuous integument surrounding it, leaving a 

 wide, funnel-shaped mioropyle giving access to the tip of the nucellus (of, also %, 

 208*, p. 74, representing an ovule of Oyoas), Within the nucellus a large cell 

 becomes marked out, as in Angiosperms; this is the embryo-sac. The embryo-sac 

 becomes filled with an extensive tissue, the endosperm, and produces at its apical 

 end (towards the mioropyle) a number of egg-cells. These vary in number from 

 2-15 in various Qymnosperms, but in any case they are all assembled together 

 beneath the mioropyle. Associated with each egg-cell is a neck, recalling that 

 structure in the archegonium (or amphigonium) of Ferns (o/. p. 67), Fig, 816' 

 shows the tip of a gymnospermio ovule in section, considerably enlarged. Note 

 the funnel-shaped mioropyle (witli germinating pollen-grains in it) and two large, 

 oval egg-cells in the endosperm below. The slight shading above the tips of the 

 two egg-cells indicates the necks. The contents of the egg-cells in this flgUrs have 

 already given rise to several cells, as in the stage represented fertiliaation has just 

 occurred. The cells hero shown in Ephedra (%. 815 '), or in most other Gymno- 

 sperms a limited number of cells (often four) cut off at the base of each egg-osll, 

 develop into little embryos, of which, however, ultimately one only survives for each 



