CELL DIVISION IN EGGS OF CREPIDULA. 



575 



X. Effects of Hypertonic Sea Watee. — (Continued.) 

 1. NaCl Added to Sea Water. 



No. 



Stage. 



Per 

 Cent. 



Time in 



Eesults. 



Solution. 



Normal S. W. 



(6) 



994 (1) 

 (2) 

 (3) 



(4) 



(5) 



1,187 (1) 



(2) 



(3) 



(4) 



(5) 



1-4 cells. 



1-20 cells. 

 1-20 cells. 

 1-20 cells. 



1-20 cells. 



1-2 cells. 



1-2 cells. 



1-2 cells. 



1-2 cells. 

 1-2 cells. 



1-2 cells. 



4 

 1 



2f hrs. 



2f hrs. 

 4 hrs. 



4 hrs. 



4f hrs. 



5 hrs. 



4 hrs. 



4 hrs. 



4 hrs. 

 4 hrs. 



4 hrs. 



36 hrs. 



8 days. 



Ohrs. 



Ohrs. 



36 hrs. 



Ohrs. 



Ohrs. 



19 hrs. 



30 hrs. 

 44 hrs. 



67 hrs. 



4-60 cells; first and second cleavage of yolk may be 



suppressed; karyomeres, polyasters. 



Ca. 100-150 cells; nearly normal; few karyomeres. 



1-20 cells; no cleavage; cytasters; polyasters. 



1-20 cells; plasma, nuclei and spindles shrunken; no 

 cleavage; many cytasters and polyasters. 



1-40 cells; very irregular cleavage; karyomeres, poly- 

 asters. 



1-2 cells; plasma, nuclei and spindles shrunken; 

 scattered chromosomes; polyasters. 



1-4 cells; cytasters are present during approach of 

 pronuclei; some furrows suppressed. 



Ca. 30-40 cells; yolk cleavage may be suppressed; 

 macromeres may be isolated; karyomeres. 



Ca. 60-70 cells; similar to preceding. 



Ca. 80-100 cells; karyomeres or tabulated nuclei always 

 occur where yolk cleavage is suppressed. 



Gastrula stages; similar to preceding. 











2. MgCk Added to Sea Water. 



No. 



Stage. 



Per 



Cent 



T 



me in 



Results. 













Solution. 



Normal S. W. 





833 



1-2 cells. 



2 



9 hrs. 



9 hrs. 



First and second cleavages of yolk suppressed; heap of 

 micromeres on unsegmented yolk; polyasters, karyo- 

 meres; very abnormal cleavage. Figs. 200, 208. 



834 



1-2 cells. 



3 



9 hrs. 



9 hrs. 



Similar to preceding. Fig. 199. 



835 



1-2 cells. 



4 



9 hrs. 



9 hrs. 



Similar to preceding; many micromeres large and con- 

 tain yolk; spindles deep in yolk. 



841 



1-2 cells. 



2 



5 hrs. 



17 hrs. 



Yolk cleavage partially suppressed; heap of micromeres 

 on unsegmented yolk; polyasters, karyomeres; chro- 

 mosomes scattered. 



842 



1—4 cells. 



4 



5 hrs. 



17 hrs. 



First and second cleavages of yolk largely suppressed; 

 26-36 cells in eggs which had passed 4-cell stage ; heap of 























micromeres; polyasters, karyomeres. Figs. 197,218. 



845 



1-4 cells. 



2 



4 hrs. 



16 hrs. 



24-36 cells in eggs which had passed 4-cell stage, nearly 

 normal; if first and second cleavages suppressed, 

 heap of micromeres on yolk. 



846 



1-4 cells. 



4 



4 hrs. 



16 hrs. 



First and second yolk cleavages suppressed; heap of 

 micromeres; polyasters, karyomeres; 24-36 cells of 

 normal types. Figs. 214-216. 



866 



lcell. 



1 



14* hrs. 



Ohrs. 



24 cells; normal except that plasma and chromatin are 

 shrunken a little. 



867 



1-8 cells. 



8 



fhr. 



61 hrs. 



First and second yolk cleavages suppressed; polyasters, 

 karyomeres; 16-24 cells in normal types. Figs. 41, 

 219. 



First and second cleavages suppressed; heap of micro- 



868 



1-4 cells. 



8 



fhr. 



10* hrs. 













meres; polyasters, karyomeres; many nuclei lobed, 













constricted, double; older stages normal. 



991 



1-8 cells. 



1 



18 hrs. 



Ohrs. 



First and second cleavages suppressed; spindles and 

 nuclei shrunken; ca. 24 cells of normal type. Figs. 

 198. 



First and second cleavages suppressed; karyomeres 



992 (1) 



1-8 cells. 



4 



3 hrs. 



lhr. 













due to failure of chromosomes to fuse. 



(2) 



1-8 cells. 



4 



3 hrs. 



141 hrs. 



1-2-cell stages have produced very abnormal forms; 



2-8-cell stages have produced normal forms with 



29-44 cells. 

 Similar to preceding; late stages with 64-70 cells; 



(3) 



1-8 cells. 



4 



3 hrs. 



27 hrs. 













karyomeres. 



