340 



BOTANY 



these division-walls are then formed, so as to divide the peripheral protoplasm 

 into " areoles," which are at first open below. With the following nuclear divi- 

 sions the embryo-sac is gradually filled with a continuous tissue, the ganieto- 

 phyte, or " Endosperm," as it is usually termed in the Spermatophytes. 



Archegonium. The archegonia (Figs. 305, F, 306) maybe found in large 

 numbers over the whole of the upper part of the gametophyte (Sequoia), or they 

 may be much fewer in number, and restricted to the apex of the gametophyte, 



PIG. 305. Sequoia sempervirens. A, ripe cone (natural size). B, scale from 

 young cone, showing an ovule, o, and resin-duct, r (x 30). C, section of young 

 ovule showing integument, in, and young sporogenous tissue. D, nucellus of 

 an older ovule, the sporogenous cells divided. E, sporogenous cell divided into 

 four (X 275). F, young archegonium. G, young embryo (X 275). (B, E, F, G, 

 after SHAW.) 



as in Pinus. In the Cupressinese they are close together. The neck may con- 

 sist of but two cells (Sequoia), or there may be several (Pinus). In Abies the 

 neck-cells are in two tiers. The egg-cell is very large in the Abietinese, and 

 presents a peculiar foamy appearance. Surrounding it is a well-defined layer 

 of cells, some of whose nuclei pass into the egg-cell before fertilization. Usually 

 a ventral canal-cell is cut off from the egg, but this is probably not the case in 

 Sequoia and some Cupressinese. 



