CELL DIVISION IN EGGS OF CREPIDULA. 



571 



IX. Effects of Diluting Sea Water with Fresh Water. — (Continued.) 







Dilution. 



Time in 





No. 



Stage. 











Kesults. 















Salt. 



Fresh. 



Dilute. 



Normal. 





(4) 



1-4 cells. 



lpart 



lpart 



2 hrs. 



44hrs. 



100-120 cells; similar to preceding. 



(5) 



1-4 cells. 



1 



1 



2hrs. 



52hrs. 



Early gastrulae; many normal; some framboisia; 

 karyomeres in endoderm cells. 



1,183 (1) 



24-48 cells. 



1 



1 



7jhrs. 



Ohrs. 



Large cleavage cavity between macromeres and 

 micromeres; scattered chromosomes, irregular 

 nuclei, daughter nuclei do not become achromatic. 



(2) 



24-48 cells. 



1 



1 



7* hrs. 



16i hrs. 



40-70 cells; cleavage cavity enormous, micromeres 

 arched over it and nearly separated from yolk; 

 karyomeres, irregular nuclei; dividing cells may 

 contain heaps of peripheral granules. 



1,184 (1) 



2-52 cells. 



1 



1 



3hrs. 



3§ hrs. 



Large cleavage cavity; a few eggs show scattered 

 chromosomes, karyomeres, and lobulated nuclei. 



(2) 



2-52 cells. 



1 



1 



3hrs. 



23 hrs. 



Ca. 52-80 cells; similar to preceding; exogastrula?. 



(3) 



2-52 ceUs. 



1 



1 



3hrs. 



28 hrs. 



Ca. 52-80 cells; similar to preceding. 



(4) 



2-52 ceUs. 



1 



1 



3hrs. 



52 hrs. 



Early gastrula stage; many exogastrulse. 



1,185 (1) 



lcell. 



40 



60 



3hrs. 



Ohrs. 



1 cell; many eggs bursted; others are swollen and 

 show little distinction between cytoplasm and 

 yolk; nuclei swollen and achromatic; no mitotic 

 figures. 



1-20 cells; cleavage generally normal; in a few cases 

 macromeres isolated, or cleavage suppressed. 



(2) 



lcell. 



40 



60 



3 hrs. 



15 hrs. 















(3) 



lcell. 



40 



60 



3hrs. 



40 hrs. 



Ca. 40-50 cells, normal. 



1,186 (1) 



1-8 cells. 



1 



1 



3hrs. 



15 hrs. 



Ca. 8-30 cells; in many eggs yolk cleavage sup- 

 pressed; some blastomeres abnormal in position or 

 size, others isolated; scattered chromosomes, 

 chromatic connections between daughter nuclei, 

 karyomeres, synkaryonts. 



(2) 



1-8 cells. 



1 



1 



3hrs. 



39 hrs. 



Ca. 40-60 cells; cleavage often abnormal or sup- 

 pressed; many fused and partial eggs; scattered 

 chromosomes, karyomeres and synkaryonts are 

 abundant. 



(3) 



1-8 cells. 



1 



1 



3hrs. 



50 hrs. 



Ca. 50-70 cells; similar to preceding. 

 Ca. 70 cells to early gastrula; many partial or fused 

 eggs; scattered chromosomes, karyomeres and 



(4) 



1-8 cells. 



1 



1 



3hrs. 



64 hrs. 



























synkaryonts. 



(5) 



1-8 cells. 



1 



1 



3hrs. 



87 hrs. 



Early and late gastrulae; some normal, others 

 abnormal; some eggs fused, others partial; 

 karyomeres and synkaryonts. 



