462 Ferguson. — The Development of the Egg and 
the nucleus containing a nucleolus which stains with avidity, 
generally contains, also, innumerable secondary nucleoli ; at 
the same time there are comparatively few deeply staining 
granules in the cytoplasm of the egg. 
The position of the secondary nucleoli with reference to 
the primary nucleolus is frequently such as to indicate that 
the former originate in the latter (Figs. 54, PL XXIV, and 
88, PL XXIII). The only observations which would militate 
against such an origin are the few cases found in which the 
secondary nuclei seem to appear earlier than the primary 
nucleolus (Fig. 29). It may be that, in these cases, the 
primary nucleolus has not yet become differentiated in struc- 
ture from the secondary nucleoli, as would evidently be true 
in a stage slightly younger than that shown in Fig. 32 ; or 
it may be true that the primary nucleolus is present, but 
fails, at this time, to stain. 
The nuclei of the cells surrounding the young archegonia 
contain from three to five nucleoli, and one or more nucleolus- 
like structures may be present in the cytoplasm of these cells. 
Each nucleolus is surrounded by a clear court which, as 
Zimmermann (’ 96 ) has pointed out, is evidently not an arte- 
fact. These nucleoli may be spherical, elliptical, irregular, 
or long and almost dumbbell-like in outline. The ordinary 
cells of the prothallium do not now show nucleoli. If such 
bodies be present, they are small and obscured by the nuclear 
reticulum. At about the time of the cutting off of the ventral 
canal-cell, many small, nucleolus-like masses appear in the 
nuclei of the sheath-cells — twenty or more occurring in a 
single nucleus. When the egg has reached maturity, and 
during the later stages of its history, no nucleolus, or but one 
or two nucleoli, can be demonstrated in the nuclei of the 
sheath-cells. These nucleoli are no longer surrounded by a 
hyaline court, but are embedded in the chromatic network. 
The nucleoli of the sheath-cells present the same attitude 
towards stains as does the nucleolus of the egg-nucleus. But 
while the nucleoli of the sheath-cells frequently stain but 
feebly, they rarely fail entirely to stain. 
