^92 Marquette, Manifestati ons of polarity in plant cells wbich usw. 



rliey are more evenly distributed, as a result tlie figure appears 

 ligliter in tlie middle than at the ends. The cell from which figure 

 (j is taken shows in addition to this a narrow light streak across 

 the equatorial region of the eonnecting fibers which is not repro- 

 duced in the figure. Whether this light streak is a regulär 

 occurrence in comiection with cell-plate-formation and what its 

 relation is to Timberlake's 1 ) ..orange zone" I have not determined. 



When the chroniosomes have about reached the poles and are 

 crowding closer and eloser together they accupy a space which in 

 section is approximately kidney shaped, the coneave side facing 

 the pole. Soon the new nuclear niembrane appears, the daughter 

 nuclei steadily increasing in size during this period. The chromatin 

 for a time appears to be arranged in a more or less Spiral fashion, 

 the irregulär contours of the Strands indicate that it is in process 

 of being distributed through the nuclear cavity. (Fig. 7.) The 

 nucleoles also raake their appearance at this stage. The first in- 

 dication of their presence is the appearance of front one to several 

 faintly staining masses lying between the material of the chronio- 

 somes- At first the boundaries of these masses are indistinct 

 gradually passing over into the clear nuclear sap. later however, 

 they become more and more definite. and at the same time the 

 affinity of the material of the masses for stains increases until 

 finally completely formed nucleoles are present. 



During these ebanges in the daughter nuclei the polar structures 

 have considerably increased in size. Frequently at this time the 

 starch contained in them stains with especial intensity so that the 

 whole cell with its violet chromatin, bitte gray eonnecting fibers, 

 and deep blue starch grains presents a striking appearance. 



As was previously mentioned the content of any particular 

 starch body seems to fluetuate with the stages of cell-division, but 

 it is difücult to deeide with certainty whether there is more starch 

 in a cell at any particular stage of mitosis than at another because 

 of the great individual variations between cells in regard to their 

 starch content. Tlie indications are, however. that the starch 

 decreases in amount during the prophases and that that which is 

 present comes to stain less intensely. This condition continues 

 until into the telophases when the starch grains again appear to 

 become more nunierous. and also to take a deeper stain. That 

 such a periodic fluetuation in the starch content of the polar 

 structures actnally exists is made probable by the fact that in 

 examining a large number of preparations it is only here and there 

 that a cell appears which shows abundant starch in the anaphases 

 or in the late prophases at the same time one frequently finds 

 cells in the telophases whose polar structures are closely packed 

 with starch. This Observation would be fairly convincing as to a 

 consuniption of starch during spindle formation. possibly also during 

 the time that the chroniosomes are passing to the poles, and its 



J ) Timberlake. H. (}-. The Development and funetion of tlie cell plate 

 in higher plants. (Bot. G~az. Vol. XXX. 1900. p. 97.; 



