MALE REPRODUCTIVE CELLS 



435 



FIG. 390. Telophase of the first reduction division in 

 Magnolia, x 1800. 



much smaller nucleolus. A nuclear membrane is present and the chro- 

 matin is to be seen as scattered granules on the newly formed skein of 

 achromatic material. The 

 cytoplasm of the cell is 

 constricted in the plane 

 of future division. 



Before this cytoplasmic 

 division has taken place, 

 however, the second reduc- 

 tion division has started 

 (Fig. 391). The two fig- 

 ures of this process occur 

 at the same time and usu- 

 ally at right angles to one 

 another. This is very 

 convenient as a control 

 for further observations. 

 The darker cytoplasmic 

 zone as seen in the first 

 division, and which was lost in the short, intermediate, resting stage, 

 is now re-formed around each of the two new figures. 



The last figure (Fig. 392) shows the results of these two divisions, 

 four small cells all lying in the same capsule or cell-wall which was formed 



by the original pollen 

 mother cell division. The 

 reduction divisions have 

 thus resulted in four cells. 

 The nuclei of these four 

 cells but rarely appear in 

 any one given section, 

 owing to the position of 

 the spindles by which they 

 were formed being at right 

 angles to each other. Thus 

 the section from which 

 Figure 392 was drawn was 

 cut obliquely through the 

 group, and two of the nu- 

 clei are only cut near their 

 periphery and present a 

 smaller section. 



The young cells' now develop a cell-wall of their own of very peculiar 

 pattern, with external spikes of knobs, and having broken out of the 



FIG. 391. Beginning of the second reduction division in 

 Magnolia. The two spindles have formed at right angles 

 to each other, thus permitting two views of the figure in 

 one section. X 1 800. 



