i 



CELL DIVISION IN EGGS OF CREPIDULA. 



571 



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



Dilation. 



Stage. 



1-4 cells 

 1-4 cells 



1,183 (1) 



24-48 cells 



Salt. 



lpart 



24-48 cells. 



1,184 (1)' 2-52 cells. 



1,185 



1,186 (1) 



2-52 cells. 

 2-52 cells. 

 2-52 cells. 

 1 cell. 



lcell. 



lcell. 

 1-8 cells 



1-8 cells. 



1-8 cells 

 1-8 cells 



1-8 cells. 



Fresh. 



lpart 



Time in 



2hrs. 

 2hrs. 



7J hrs. 



7£hrs. 



3 hrs. 



3 hrs. 

 3 hrs. 

 3 hrs. 

 3 hrs. 



3 hrs. 



3 hrs. 

 3 hrs. 



3 hrs. 



3 hrs 

 3 hrs 



3 hrs 



Normal 



44 hrs. 

 52 hrs. 



Ohrs. 



16£hrs. 



3Jhrs. 



23 hrs. 

 28 hrs. 

 52 hrs. 

 Ohrs. 



15 hrs. 



40 hrs. 

 15 hrs. 



39 hrs. 



50 hrs. 

 64 hrs. 



87 hrs. 



Results. 



100-120 cells; similar to preceding. 



Early gastrulffl; many normal; some framboisia; 



karyomeres in endoderm cells. 

 Large cleavage cavity between macromeres and 



micromeres ; scattered chromosomes, irregular 



nuclei, daughter nuclei do not become achromatic. 

 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. 

 Large cleavage cavity; a few eggs show scattered 



chromosomes, karyomeres, and lobulated nuclei. 

 Ca. 52-80 cells; similar to preceding; exogastrulse. 

 Ca. 52-80 cells; similar to preceding. 

 Early gastrula stage; many exogastrulae. 

 1 cell; many eggs bursted; others are swollen and 



ytopl 



yolk; nuclei swollen and achromatic; no mitotic 



figures. 



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



macromeres isolated, or cleavage suppressed. 



a. 40-50 cells, normal. 



a. 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. 

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

 pressed; many fused and partial eggs; scattered 

 chromosomes, karyomeres and synkaryonts are 



abundant. 



a. 50-70 cells ; similar to preceding. 



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



e&gs* ana ++ ar °A nhrnmnnnmpx. karvomeres and 



lynkaryonts. 



and late gastrulae 



some 



rmal 



abnormal; some eggs fused, others partial 

 karyomeres and synkaryonts. 







