﻿258 BOTANICAL GAZETTE [april 



In some cases and at a later stage a large part of the daugh- 

 ter spireni is quite regular, presenting a series of long and more 

 or less uniform turns, so that when seen from the pole, the 

 spirem appears in the form of a wreath or crown {^fig- n)- This 

 regularity is rather the exception than the rule, since in the 

 majority of cases much of the spirem consists of irregular turns 

 varying In size. It seems probable that were all the grand- 

 daughter elements rods, which form V's, the spirem would be 

 quite regular; but, as often happens, when these elements arrive 

 at the poles in the form of V's, double U's, and contorted rods 

 intermingled, a very irregular spirem must result. 



Strasburger, Guignard, and Gregoire state without reserve 



that the loops of the spirem (y?^. //) represent the V's and U's 

 of the previous karyokinesis. This may be true, but the state- 

 ment for Lilium, and more especially for other plants to be 

 mentioned later, is purely a deduction. The spirem is often, if 

 not always, continuous, as Strasburger also asserts, and the iden- 

 tity of the individual chromosomes is lost. It is true that in 

 Lilium the daughter nucleus does not pass into that structure 

 known as the complete resting stage, yet during the construc- 

 tion of the daughter spirem the chromosomes do to some extent 

 become reticulated, so that the second mitosis may have for its 

 purpose something more than the equal distribution of the 

 granddaughter chromosomes to the four granddaughter nuclei. 

 This seems especially true in those plants in which the daughter 

 nuclei pass into the resting stage or approach it more closely 

 than in Lilium. 



The division of the daughter nucleus in the pollen mother- 

 cell of Lilium and in other phanerogams as well, has been a 

 stumbling block to every cytologist who has studied the prob- 

 lem. So complex is the process, especially the behavior of the 

 chromatin, and so numerous are the difficulties attendant upon 

 its study, that it is little wonder that errors have been made and 

 that several different explanations have seemed at the time 

 equally correct. 



As I have shown in former publications, the spindle of the 

 second mitosis develops as a multipolar structure, arising in a 



