378 



VEGETABLE GROWTH. 



somewhat lengthened in the direction of the long axis of the cell, 

 and contains several nucleoli. When it begins to grow, these 

 nucleoli disappear, and the characteristic striation previously de- 

 scribed appears transverse to the direction of future division and 

 of the nuclear disc. The latter is not clearly defined, and its 

 halves do not recede from one another very far, since, in fact, 

 there is not space for much expansion in any event. The parti- 

 tion wall at first is confined to the space between the halves, 

 and these are found in close contact with it, but later it extends 



completely across. The remarkable thickness of the radial walls 

 of the cambium is explained by Sanio as due to the non-absorp- 

 tion of a part of the mother-cell ; but Strasburger ascribes it 

 to the uninterrupted nutrition of the radial wall from the contents 

 of the cell itself. The newly formed partition-wall is thin, and 

 cannot be shown by reagents to be double. 1 



1 The student should consult Strasburger's work : Ueber den Theilungs- 

 vorgang der Zellkerne, 1882 ; also Das botanische Practicum, chap, xxxiv. 



FIG. 166. Behavior of nucleus during cell-division In the endosi>erm of Allium to 

 illustrate the extraordinary complexity of the stained bodies. The dark lines represent 

 the chromatin. (Flemming.) 



