igiS] YASUI—DIOSPYROS KAKI 369 



27 in no. 1 (pi. fig. 11). In D. virginiana Miss Hague counted 30 or 

 more. 



The longitudinal division of the chromosomes in preparation 

 for the homotypic division occurs in metaphase, and at telophase 

 the chromosomes become arranged in the spireme and spread over 

 the outer cavity of the daughter nucleus. The number of chro- 

 matin granules is not the same as the x number of chromosomes; 

 and there appear two or three nucleoli in the daughter nucleus 

 (pi. fig. 12, a, b). The homotypic division of the microspore 

 mother cell occurs in the usual way. The two axes of the spindle 

 fibers of this division are not in any definite relation to one another 

 (pi. figs. 13, 14). In wall formation the microspores are in tetra- 

 hedral arrangement (pi. figs. 15, 16), and the mother cell wall, 

 which becomes mucilaginous and separates the four young micro- 

 spores (pi. fig. 17), disappears gradually with the formation of the 

 thick wall of the pollen grain. 



At the same time the uninucleate tapetal cells enlarge and 

 become multinucleate. These divisions of the tapetal nuclei are 

 mitotic at first, but later they become amitotic, after which they 

 begin to disorganize when the homotypic division of the mother 

 cell has been completed (pi. figs. 20, 21, 22). 



The mature pollen grain is spherical, with remarkable canals 

 upon the surface of the wall (pi. fig. 18). The cytoplasm occurs 

 as a thin layer surrounding a large central vacuole. In general 

 only a single nucleus was observed in the pollen grain, pi. fig. 19 

 representing the only specimen in which two nuclei were observed. 



The foregoing account of microspore formation was obtained 

 from material of no. 1. I have investigated no. 3 also, but could 

 not determine the number of chromosomes. The pollen grain is a 

 little larger than in the case of no. 1. The anther of no. 3 contained 

 many withered pollen grains. 



Development of pistillate flower 



The pistillate inflorescence usually appears upon an upper 

 branch, consisting of one flower and two bracts that suggest the 

 position of flowers that have disappeared. The bracts usually 



