THE CHROMOSOMES 



93 



lost the satellite, the constriction, and part of the organizer the remaining 

 portion of the organizer forms a nucleolus. 





1 »» 



?/ . a **fl^ 



Fig. 65. — Spiral chromonemata in chromosomes, a, chromonemata in microsporocjrte 

 of Trade scaiitia after removal of chromosome matrix with hot water. {After T. Sakamura.) 

 b, chromosomes in microsporocyte of Trillium, showing the major coils and in certain 

 regions (at top, faintly) the minor coils. {Photograph by A. W. S. Hunter. After C. L. 

 Huskins.) c, nucleus of a protozoan {Spirotrichonympha) ; each of the four chromosomes is 

 attached to the nuclear membrane by a fiber. Compare Fig. 66. {After L. R. Cleveland.) 



Fig. 66. — Three drawings of a telophase nucleus of a protozoan {H olomastigot aides) . 

 a shows the major and minor coils of the chromonemata; b shows only the major coils; 

 c shows the larger sup^rcoils which result from the elongation of the chromosomes. Com- 

 pare Fig. 6.5, c. {Courtesy of L. R. Cleveland.) 



In some plants, e.g., Trillium and Tradescantia, the meiotic chromo- 

 somes at metaphase and anaphase are extremely large. Their coiled 

 chromonemata appear \^ith admirable clarity in good preparations 

 (Fig. 65), and they can easily be watched while being suljjectod to various 



