CELL DIVISION IN EGGS OF CREPIDULA 



569 



No. 



1,163 



1,164 

 1,165 

 1,166 



1,167 (1)1 



(2) 





1,168 (1) 



(2) 

 1,169 (1) 



(2) 



(3) 



l,169a(l) 



(2) 

 (3) 



(4) 



l,169bl) 



(3) 



(4) 

 (5) 



VIII. Effects of Carbonic Acid. 



Stage. 



1-8 cells 



1-8 cells. 



1-8 cells. 



1-30 cells. 



1 cell. 



Sea Water. 



Charged . 



lcell. 



1-30 cells 



1-30 cells 



1-2 cells 



1-2 cells. 



1-2 cells. 



1-4 cells. 



1-4 cells 



1-4 cells 



1-4 cells 

 1-4 cells 



(2) 1-4 cells 



1-4 cells 



1-4 cells 



1-4 cells 



1 part 



1 

 1 

 1 



1 



1 



1 



1 



1 



1 



1 



1 



1 



1 



1 

 1 



1 



1 



Normal 



1 part 



1 

 1 

 



1 



1 



1 



1 



1 



1 



1 



1 



1 



1 



1 



1 



1 



1 



Normal sea water 



1 



1 



Normal sea water 



1 



1 



Normal sea water 



Duration. 



Results 



28 hrs. Cell membranes usually granular and wrinkled ; lobes 



and spinning threads present ; surface tension reduced ; 

 nuclear membrane also wrinkled and lobulated. 

 giving appearance of amitosis; chromatin dense and 

 achromatin scanty in resting nuclei ; resting spheres 

 lie at surface of cell, as in normal eggs ; mitotic figures 

 rmal ; cleavage very irregular and often suppressed . 



28 hrs. 

 28 hrs. 

 28 hrs. 



7 hrs. 



Figs. 119, 120, 122-129, 131. 

 Same as preceding. 

 Same as preceding. 



Similar to preceding; resting nuclei much lobulated 

 if in amitosis. 



1 



nkl 



i" JT / - — - 



mitotic figures normal ; positio] 

 and cytoplasm dependent up 

 constriction. 

 28 hrs. 120-40 cells; similar to precedi 



densely chromatic 



44 hrs 



20 hrs 



18 hrs 



ig; many abnormal 



is of surface tension, 



1-30 cells; in addition to preceding modifications 



chromosomes may be widely scattered and cytoplasm 



coarsely granular. 



4-52 cells; similar to preceding; many karyomeres and 



1 



gul 



normal or verv abnormal 



micromeres and nuclei go through 



25 hrs 



ippressed 



lobulated 



42 hrs 



3 hrs 



26 hrs 



44 hrs 





50 hrs 

 6 hrs 



24 hrs 



24-48 cells; macromeres may be separated from one 

 another and micromeres may go through center of 



egg to vegetal pole. 

 64-68 cells; many eggs fused in pairs; fusion always 

 between entomeres ; nuclei always at surface and not 



buried along line of fusion. 



1-4 cells; chromatin clumped in resting nuclei; sphere 

 outlines very distinct, especially on side away from 

 animal pole; chromosomes scattered; in first cleavage 

 yolk lobe and polar bodies are carried in with furrow 

 to Zwischenkorper f and no new membrane is formed 

 until after constriction is completed. 



8-25 cells ; cleavage normal in most eggs ; suppressed in 



a few. 

 4&-52 cells; normal in most cases; first and second 



cleavages suppressed in a few eggs. 



52-64 cells; similar to preceding. 



1-8 cells ; some cleavages suppressed ; many spindles dis- 

 placed and chromosomes scattered; many spindles 

 distorted ; many lobes on cells. 

 -8 cells; similar to preceding; cells and nuclei lobulated; 

 many scattered chromosomes and karyomeres, 



m-ossed cleavaces and distorted spindles. 



1 



24 hrs. 

 11 hrs. 



sup- 



24 hrs 



25 hrs 

 24 hrs 



8-30 cells ; many irregular cleavages with lobulated 

 separated macromeres. 



30-50 cells; cleavage very abnormal; many eggs fused. 



48 hrs! 1 60-80 cells; very abnormal cleavage; many fused 



egg 8 - • 



.'• 



