CELL DIVISION IN EGGS OF CREPIDULA. 



573 



No 



825 



827 



828 



829 



830 



831 



832 



839 



840 



843 



844 

 861 



862 



863 



864 



865 



965 



966 



967 



968 



969 



Stage. 



1-2 cells. 



1-20 cells. 



1-20 cells. 



1-20 cells. 



1-20 cells. 



1-20 cells. 



1-20 cells. 



1-4 cells. 



1-4 cells. 



1-4 cells. 



1-4 cells. 

 1-4 cells. 



1 cell. 



1-4 cells. 



1-4 cells 



1-4 cells 



20-30 cells. 



20-30 cells. 



1-20 cells. 



1-20 cells. 



4-12 cells. 



X. Effects of Hypertonic Sea Water.— {Continued.) 



1. NaCl Added to Sea Water. 



Per 



Cent. 



2 



t 



1 



2 



3 



4 



1 



2 



1 



2 



i 



1 



2 



3 



4 



1 



1 



1 



1 



2 





Time in 



Solution . 



Normal S. W 



16hrs. 



9hrs. 



2hrs. 



9hrs 



9hrs 



2 hrs 



2 hrs 



6hrs 



6hrs. 



6hrs. 



6 hrs 

 13 hrs 



4 hrs 



2ihrs 



2 hrs, 

 3* hrs 



2hrs 



3 hrs 



16 hrs 



16 hrs 



16 hrs 





3 hrs 



23 hrs. 



8 hrs. 



6£hrs. 



18 hrs. 



32 hrs. 



6 J hrs, 

 6Jhrs 



20 hrs 



20 hrs 



15 hrs 



15 hrs 

 Ohrs 



10 hrs 



10 hrs 



10 hrs. 

 10 hrs. 



10 hrs 



Ohrs 



Ohrs 



12 hrs 



24 hrs. 



Ohrs. 



Results. 



2 cells; no cleavage; karyomeres, polyasters; some 

 nuclei large, thin walled and achromatic, others 

 contain large, dense nucleolus; many nuclei con- 

 stricted and lobed as in amitoas. Fig. 202. 

 a,. 2-50 cells; cleavage irregular; yolk cleavage usually 

 suppressed, sometimes increased; karyomeres; many 



polyaste 

 ones. Figs 



stages less modified than 



cells; very abnormal cleavage; yolk cleavage sup- 

 pressed, plasma cleavage active; polyasters, scattered 

 chromosomes, karyomeres. Fig. 222. 



Ca. 1-60 cells; cleavage very irregular; yolk divides 

 seldom; many polyasters, karyomeres. 



Ca. 1-70 cells; cleavage nearly suppressed; many poly- 

 asters, karyomeres, which stain faintly; clear, un- 

 stained nucleoli. Fig. 207. 



Ca. 1-30 cells; no polyasters or karyomeres, chromo- 

 somes widely scattered; nuclei flattened in polar axis. 



1-20 cells; yolk cleavage suppressed; karyomeres, 



stages nearly normal 



axis: ad van 



Ca. 1 



cleavage suppressed; polyaste 

 ;' scattered chromosomes; bunch of n 

 unsegmented yolk. 



i; yolk cleavage suppressed; polyast» 

 : chromosomes widely scattered. 



30-40 cells; yolk cleavage suppressed; polyasters 



advanced stages normal 



205 



v,«. 2-40 cells: similar to preceding. 



20-40 cells; almost normal; yolk cleavage occurs; few 



polyasters. 

 Ca. 2-24 cells; yolk cleavage more or less suppressed; 

 many polyasters and karyomeres; heaps of micro- 



meres. 



advanced stages normal ; yolk cleavag 



pressed; many polyasters and heaps of micromeres 



Figs. 204 



cleavage irregular; yolk cleavage 



or less suppressed; many polyasters and karyomeres 



Kg. 211. . x . ,. 



3a. 1-30 cells; cleavage less irregular than preceding; 



few polyasters and karyomeres ; later stages normal . 



Figs. 209, 212. . . _ , . , 



20-30 cells ; plasma, nuclei and spindles shrunken and 



plasmolyzed. , . . — i 



20-36 cells; little if any cleavage; plasma, nuclei, and 



spindles much shrunken and plasmolyzed. 

 Ca. 1-40 cells; earlier stages show suppressed, or in- 

 creased, yolk cleavage ; polyasters, and karyo- 

 meres: scattered chromosomes, chromatic connec- 



tions between daught 

 abnormal 



nuclei; older stages less 



1-64 pells- 'abnormalities similar to preceding; some 

 1L fuid together, others with isolated macromeres. 



«fE2U nuclei and spindh* shrunken; * 

 resting nuclei chromatin clumped ra middle of 

 £3 dS o? achromatin; in mitosis «M« £ £ 

 definite area of achromatin; plasma gathers m 



cleavage furrows 



