Division in the Root of Vicia Faba. 167 
the general literature on cell division, is that of Dr. T. Mont- 
gomery, entitled, ‘Comparative Cytological Studies with 
Especial Regard to the Morphology of the Nucleolus.”” His 
observations are based upon animal cells and his conclusions, 
briefly stated, are as follows: 
Number of Nucleol.—The nucleoli vary in number from 
one to five and in certain stages of some cells—there may be 
several hundred. In a few cells no nucleoli are present. 
Position of the Nucleolus in the Nucleus —When a single 
nucleolus is present it is always placed excentrically though 
not against the nuclear membrane. Those cases where it 
occupies the centre of the nucleus are to be regarded as 
exceptional. In regard to this point the author says he is 
unable to agree with Professor Macfarlane, who believes the 
nucleolus to be the morphological and trophic center of the 
cell. 
The nucleolus is often suspended in the chromatin network, 
but not in such a way that the fibers penetrate its substance ; 
they are merely wound around it. 
General Morphological Structure of the Nucleolus—The 
nucleolus may or may not have a membrane. Vacuoles are 
normal structures in nucleoli since they may be seen after the 
most diverse methods of fixation. To the nucleolini or 
endonucleoli which Professor Macfarlane regards as “the 
tropic center of the cell and as an important mechanical agent 
during nuclear division,” the author attaches no morphological 
significance. 
Amceboid movements have been frequently observed in 
nucleoli and these are in all probability normal, and perhaps 
should be considered as an inherent function of the nucleolus, 
since no movements in other parts of the nucleus are known 
in a resting cell. 
Nucleolar division is of two kinds: (1) The mode by 
which the nucleolus becomes elongated and then breaks into 
