IO6 MARGARET C. FERGUSON 



(figs. 205 and 208) ; it may show a weak reaction to these stains 

 (fig. 209), or it may be absolutely unaffected by them, remaining 

 as a hyaline or greenish yellow structure (fig. 210). When the 

 nucleolus resists the action of dyes, its nucleus is usually totally 

 free of the secondary nucleoli, which have been described in 

 connection with the maturation of the egg-nucleus, and the 

 cytoplasm of the egg is studded, to an unusual degree, with 

 large, deeply staining granules. But 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. 227, plate XX, and 208, 

 plate XIX). The only observations which would militate 

 against such an origin are the few cases found in which the 

 secondary nucleoli seem to appear earlier than the primary 

 nucleolus (fig. 195, plate XVII). It may be that, in these cases, 

 the primary nucleolus has not yet become differentiated in 

 structure from the secondary nucleoli, as would evidently be 

 true in a stage slightly younger than that shown in fig. 202, 

 plate XVIII ; or it may be true that the primary nucleolus is pres- 

 ent, but fails, at this time, to stain. Floderus ('96) describes a 

 somewhat similar origin of the paranuclei, in Tunicates, from 

 the nucleolus proper. 



The nuclei of the cells surrounding the archegonia contain 

 from three to five nucleoli, and one or more nucleolus-like struc- 

 tures 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 artifact. Debski ('97) 

 opposes this view, however, and considers the clear court to be 

 attributable to the shrinkage of the nucleolus, since he does not 

 find it when material is treated with xylol instead of cedar oil. 

 These nucleoli may be spherical, elliptical, irregular, or long 

 and almost dumbbell-like in outline. The ordinary cells of the 

 prothallium do not show nucleoli. If such bodies be present in 

 these cells they are small and obscured by the nuclear reticulum. 



