A Cytological Study of Oryza sativa L.* 



- " By 



Yoshhiari Kuwada. 



(With Plate VIII). 



Recent studies have brought to light several interesting 

 phenomena relating to the difference of chromosomes and their 

 behavior in certain plant species of very close affinities. Thus the 

 comparative studies of closely allied plant species or varieties be- 

 came a subject of certain interest. Inasmuch as some closely 

 allied plants show differences of chromosomes, while others pre- 

 sent no such tendency it is desirable to know what groups of 

 plants have generally such tendency. For the study, of the real 

 significance of this chromosome difference, investigations of cul- 

 tivated plants rich of races were suggested by Professor Fujii. 

 Such plants may be considered as plants which are liable to certain 

 changes, and it is likely that this changeable nature is correlated 

 in certain manner with the internal cellular structure, especially 

 chromosomes and their behavior. Oryza sativa L. or the rice- 

 plant, which I have chosen for the purpose of investigation is 

 the most important of the cultivated plants in Japan ; and of 

 this plant there are so many races as they are counted by 

 thousands. Among them, I have studied chiefly the race 'Shin- 

 riki,' partly the races ' Kishuwase,' 'Usuaka,' * Kurobo ' (all 

 these races belonging to subsp. Oryza utilissima Kcke.), - Kuro- 

 mochi ' and ' Akashimochi ', (these two races belonging to 

 subsp. Oryza glutinosa Lour.). So far as these races are 

 concerned, however, I could ascertain in the main only a little 

 difference of sizes of chromosomes in the maiotic phase, but an 



* A preliminary note was published under the title, '* On the Development of the 

 Pollen and. the Embryosac, and the Formation of the Endosperm, etc. of -Orizct sativa 

 L" in Japauese in this magazine, Vol. XXIII, 1909. _'■..- 



