

tec 1910/j KUWADA.-A CYTOLOG. STUD. OF ORYZA SATIVA. 275 



The disintegration of the antipodal cells seems to occur in 

 different stages, sometimes already before the fertilization, and 

 sometimes after one or two cell-layers of the endosperm tissue 

 have been formed. As soon as the nuclear membrane is dis- 

 solved, as the disintegration proceeds, bodies like * Mitokondrin ' 

 make their appearance in the cytoplasm, which are well stained 

 with Heidenhain's iron-alum-hasmatoxylin or safranin of 

 Flemming's triple staining. 



The young antipodal cells are filled up with many colourless 

 granules in the cytoplasm which turn reddish brown when treat- 

 ed with the chloriodide of zinc. The similar granules may be 

 seen in the egg-cell, synergidas, and in the cytoplasm around 

 the polar nuclei. Their occurrence here seems to be transient ; 

 but in the antipodals they remain pretty longer. These granules 

 probably represent a mixture of amyrodextrin 1 and amylose. 



The synergidae disintegrate before the fertilization. 



The fertilized egg-nucleus migrates downward and prepares 

 for division. The first division of the fertilized egg takes place just 

 after many free endosperm-nuclei have been formed. 



Before the fertilization both polar nuclei, each containing a 

 large nucleolus, come in contact with each other, but do not 

 fuse together. They migrate toward the micropylar end of the 

 embryosac, where they are to receive a male nucleus. The 

 ' double fertilization ' is indicated here by the existence of two 

 nucleoli in one of the polar nuclei, one of the two nucleoli prob- 

 ably representing the one derived from the sperm-nucleus,* 

 although I was not able to find the male nucleus itself in con- 

 tact with the polar nuclei. The male nucleus seems to unite at 

 first with the upper polar nucleus. The Figs. 21 and 22 show 

 stages just after the union of the male nucleus. The polar 

 nuclei have already well developed the chromatin-threads before 



tHuss(5). 



* Strasburgeb, (11, P. 299), in examining the passage cf the male nucleus to the 

 secondary embryosac-nucleus in living materials of Monoiro'pa, describes : " So ist der 

 betreffende Spermakern auch sehr schwer zu unterscheiden, nachdem er mit dem 

 secundaren Ernbryosackkern in Contact trat,...Deutlicher wird der Spermakern hier 

 erst, nachdem seine innere Differenzirung begonnen und, wie meist, auch ein Kern- 

 k or perch en in ihm sich zeigte." 



