﻿268 BOTANICAL GAZETTE [ APRIL 



distribution of an equal number of chromosomes to the four 

 granddaughter nuclei. 



In 1898, the writer showed clearly the striking similarity 

 between the first two mitoses in the micro- and macrospore 

 mother-cells of Hellebonis foetidus and Lilmm Martagon, and con- 

 cluded upon that evidence that the pollen and embryo-sac 

 mother-cells were homologous. The work of recent observers, 



especially Juel (1900) and Schniewind-Thies (1901), who have 

 confined their attention primarily to this phase of the problem, 

 has only confirmed this view. 



Since the chromosomes in the pollen mother-cell undergo a 

 double longitudinal division during the first or heterotypic 

 mitosis, the same w^ould seem certain also in the embryo-sac 

 mother-cell, and it was for this reason that a reinvestigation of 

 the problem in Liliwn Martagon was undertaken. 



As was expected, the first and second mitoses in the embryo- 

 sac were found to be essentially like those in the pollen mother- 

 cell. These divisions will be described somewhat in detail in 

 order to show what the embryo-sac contributes toward the solution 

 of this and other problems suggested in the preceding pages. 



As is well known, the mother-cell of the embryo-sac of Lilium 

 becomes the macrospore and develops at once into the embryo- 

 sac. The first nuclear division is heterotypic, the nucleus under- 

 going the same changes during the prophase as in the pollen 

 mother-cell. The spindle arises ^s a multipolar structure, and 

 the form and orientation of the chromosomes within the multi- 

 polar complex of fibers and upon the mature spindle present 

 nothing requiring a special description. 



Owing to the small number of macrospores in an ovary as 

 compared with the number of microspore mother-cells in an 

 anther, a much smaller number of karyokinetic figures will be 

 observed in the former, yet in the course of an extended investi- 

 gation, it seems exceedingly probable that about the same variety 

 in the form of the chromosomes exists in the macro- as in the 

 microspore mother-cell. As a rule, the daughter segments are 

 twisted upon each other and fastened to the spindle fibers by the 

 ends [Jig, 40), Only in exceptional cases can any indication of 



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