No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 38 1 



internodal cells, become multinucleolar "; the nodal leaf cells 

 proceed in the same way. From these observations Macfarlane 

 concludes : " in every active embryonic cell one nucleolus only 

 is present in the resting state"; in some cases a fluid globule 

 is present in the nucleolus, and this probably represents a 

 " degradation of the endonucleolus." " The nucleolus, or more 

 probably the nucleolo-nucleus, is the center of germinal activity, 

 and that as we pass outwards to the periphery of the cell, this 

 reproductive activity becomes less and less. . . . The result is 

 that in all plants thus examined, after cell division has ceased, 

 continued division of the cell contents from the endonucleolus 

 outwards goes on. ... I venture, therefore, to regard it as a 

 general principle that after cell formation has ceased, the cell 

 contents (especially the endonucleolus and nucleolus) persist 

 in their activity for a shorter or longer period ; . . . the most 

 exalted type of cell is one with abundant protoplasm containing 

 a single nucleus, nucleolus, and endonucleolus; ... a cell with 

 vacuolated protoplasm, one nucleus and two to four nucleoli 

 is less exalted, while the multinuclear state is the most degraded 

 form of cell." 



Zacharias ('85) gives critical reviews of numerous preceding- 

 papers on nucleoli, besides observations of his own on various 

 cells of plants. Galantlms nivalis, cells of the inner layer of 

 the " Fruchtknotenwand " : the single nucleolus is about ^^ the 

 size of the nucleus; examined in water it is homogeneous ; after 

 the action of absolute alcohol it appears to be composed of 

 granules of various indices of refraction. Bast cells of Cuciirbita 

 fc-po : the nucleoli, when stained with " Blutlaugensalz-Eisen- 

 chlorid," become very intensely colored, while the remaining 

 nuclear substance stains only faintly. In the cells of Spirogyra 

 and of the asci of Lichens he finds that there are no " nucl^oles- 

 noyaux," such as Carnoy described. " AUe Autoren stimmen 

 gegenwartig darin iiberein, dass die Nucleolen bei der Kern- 

 theilung verschwinden." In opposition to Strasburger he 

 contends that during the mitosis the dissolved nucleolar sub- 

 stance might as probably enter into the formation of the spindle 

 fibers as of the chromosomes. In Chara (observed living) each 

 nucleus contains one large nucleolus, with vacuoles : " Naht 



