THE HIGHER CRYPTOGAMIA. 429 



Shortly after the rows of cells of the pro-embryo have 

 separated from one another, the formation of the embryo 

 itself commences in the terminal cell of each row, either 

 immediately, or after the occurrence of divisions by hori- 

 zontal septa. This formation takes place by the repeated 

 division of the apical cell for the time being by means of 

 septa inclined in the first place alternately to the right and 

 to the left, and soon afterwards in three different directions. 

 The cells of the second degree divide into inner and outer 

 cells by radial, and those of the third degree by longitudi- 

 nal septa parallel to the axis, and so on, following the mode 

 of cell-multiplication in the terminal bud of Equisetum and 

 other plants (PI. LXI, fig. 11; PL LXII, figs. 9, 10). In the 

 half-ripe seed the number of rudimentary embryos is at 

 least four times as great as that of the corpuscula impreg- 

 nated. Of these however, in the greater number of cases, 

 one only is developed rapidly and vigorously ; the rest are 

 much less fully developed, shrivel up by degrees, and ulti- 

 mately die. During the formation of the embryo the 

 younger lower cells of the pro-embryo — which latter has be- 

 come the suspensor — also expand considerably in length, and 

 at last the same expansion occurs in its massive portion im- 

 mediately adjoining the embryo (PI. LXI, fig. 10 ; PI. LXII, 

 fig. 10). The latter also then become disconnected from 

 the laterally-adjoining cells (PL LXII, fig. 10), and often, 

 especially near the lower end, bear a deceptive resemblance 

 to a pro-embryo not yet broken up into its longitudinal rows 

 of cells.* 



After the penetration of the pro-embryo into the middle 

 region of the endorsperm, the walls of the corpusculum can 

 easily be separated from the surrounding tissue. They 

 exhibit now prominent reticulate ridges on the outer side, 

 corresponding in direction with the edges of contact of the 

 neighbouring cells, and they have also somewhat large flat 

 pits. These phenomena are especially manifest in Pinus 

 canadensis (PL LXII, fig. 8). In this species the upper 

 portion of the four uppermost cells of the pro-embryo are 

 normally much thickened, and then exhibit manifest 

 lamination (PL LXII, fig. 7) ; sometimes strange-shaped 



* It is doubtless from this phenomenon that some observers, especially 

 Geleznow, deny the breaking up of the pro-embryo into distinct suspensors. 



