112 MARGARET C. FERGUSON 



The central cell is very vacuolate at first, its nucleus always 

 remains close beneath the neck-cells and is more or less con- 

 cave on the side toward those cells. When the ventral canal- 

 cell is cut off, about a week before fertilization, the vacuoles 

 have nearly disappeard from the venter of the archegonium. 



The spindle in the division of the central cell arises as a 

 multipolar diarch figure and apparently lies wholly within the 

 nucleus. That portion of the mitotic figure which gives rise to 

 the ventral canal-cell varies much in the later stages of its de- 

 velopment ; but, whatever irregularity characterizes this part of 

 the spindle, it always becomes monopolar or nearly so, at its 

 lower, inner extremity. 



The form and structure of the nucleus of the ventral canal- 

 cell are very variable, and are correlated with the irregularities 

 occurring in the upper, outer portion of the achromatic spindle 

 during the division of the central cell. There are probably in- 

 stances in which no membrane is developed about this nucleus : 

 in such cases the chromosomes never fuse to form a network. 

 The ventral canal-cell rarely presents the appearance of a nor- 

 mal cell ; at the time of fertilization it usually persists as a 

 small, somewhat crescent-shaped, deeply staining body which 

 lies just beneath the neck-cells of the archegonium and above, 

 but in contact with the cytoplasm of the egg. 



As the egg-nucleus assumes its central position in the oosphere, 

 it increases much in size, and many fibers arise in the cytoplasm 

 surrounding it. These threads have, in general, a radial 

 arrangement and are more prominent along the upper side of 

 the nucleus. The structure presented by the growing, and also 

 by the mature, egg-nucleus may vary from a most delicate net- 

 work bearing minute granules to an interrupted, imperfect 

 reticulum composed of large, irregular, diffusely staining ele- 

 ments. These various aspects are doubtless the expressions of 

 the different physiological activities with which this nucleus is 

 concerned. The normal egg-nucleus has one large, vacuolate 

 nucleolus and a variable number of small, secondary nucleoli. 

 There is no evidence of the presence in this nucleus of a special 

 metaplasmic substance. 



During the maturation of the egg, many nutritive spheres 



