LIFE HISTORY OF PINUS 99 



MATURATION OF THE EGG. 



The Descent and Grozvth of the Egi^-nucletis. — The egg- 

 nucleus is no sooner formed than it begins to increase in size, 

 becoming greatly enlarged even before the disappearance of the 

 spindle-fibers (figs. 196-202). As the nucleus moves toward 

 the center of the oosphere, threads of more or less delicacy 

 extend, in a radial manner, from its wall into the surrounding 

 cytoplasm. These fibers are not equally well defined in all 

 preparations, but, whatever the degree of their prominence, 

 they are invarably more strongly differentiated about the upper 

 side of the nucleus, and may extend from the nucleus to the 

 top of the egg (figs. 202-204). 



As already stated, few, if any, vacuoles persist within the 

 the venter of the archegonium at the time of the division of the 

 central cell. Following their disappearance, there arise numer- 

 ous spherical bodies, the so-called proteid vacuoles. Coordi- 

 nate with the downward movement of the egg-nucleus, these 

 bodies assume a position about the periphery of the oosphere, 

 more especially at its base (the organic apex of Strasburger), 

 and at its sides (figs. 179, 180, plate XVI, 214, plate XIX). Un- 

 der a low power, the cytoplasm of the mature egg appears dense 

 and finely granular; the ''proteid vacuoles" do not seem to 

 differ materially from the protoplasm in which they are im- 

 bedded ; and many deeply staining granules are scattered 

 throughout the cell. With greater magnification, however, a 

 very beautiful, granular reticulum becomes apparent. There 

 is no suggestion of the alveolar structure described by Biitschli 

 ('94). At times this reticulum is ever3^where crossed by short 

 fibers which have no definite arrangment and are, apparently, 

 not confined to any fixed period in the history of this cell (fig. 

 200). The spheres in the outer and basal portions of the cyto- 

 plasm are resolved into very complex structures which, although 

 they simulate the appearance of nuclei, could never be mistaken 

 for such bodies by one familiar with cell-structures (figs. 202, 

 203.) 



No cytoplasmic radiations, similar to those described by 

 Belajeff ('91) in Taxtis baccata, and by Dixon ('94) in Piniis 

 sylvestrts, have been observed in connection with the fully 



