CELL DIVISION IN EGGS OF CREPIDULA 



567 



No 



800 



801 

 803 

 818 



819 

 877 



878 



1,180 (1) 



(2) 





1,181 (1) 



(2) 



VI. Effects of Etheb Added to Sea Water. 



Stage. 



1-8 cells. 



1-8 cells. 



1-8 cells. 



2-20 cells. 



2-20 cells. 

 1-8 cells. 



1-8 cells. 



1-2 cells. 



1-2 cells. 



1-20 cells. 



Strength, 

 Per Cent. 



Duration. 



Result*. 



1 



lhr. 



1 

 1 



5$ hrs 

 5 1 hrs 

 25 hrs 



1 

 3 



3 



25 hrs 

 *hr. 



3 hrs 



No modifications, except that cytoplasm and yolk are not 

 sharply separated. 



4-16 cells ; similar to preceding. Control in 2-8 cells. 



4-16 cells; similar to No. 800. 



Ca. 52 cells; archiplasm gathered around sphere or nucleus; 



chromatin clumped; chromosomes scattered and spindle 



fibers gone ; no signs of ami tosis. 

 Similar to preceding; control in 52 cell stage. 

 Cleavage stopped; yolk and cytoplasm intermingle; archiplasm 



gathers along cleavage furrows; chromosomes scattered; 



spindle fibers indistinct. 

 Similar to preceding; sphere granules widely scattered; centro- 



(Normal S. W. somes large; chromatin clumped in resting nuclei ; archiplasm 



2 



6 hrs.) 



gathers in cleavage furrows ; blastomeres may separate. 



2 



1 



6 hrs 



1 



2 hrs. | Many lobes and deep furrows in resting stages which bear no 



constant relations to egg axes or nuclei; clear plasma 

 bounds furrows; mitotic figures approximately normal, 

 spindle fibers distinct. 



4-16 cells; many eggs normal; a few show large polar bodies 

 and many macromeres; mitotic figures normal. All ether 

 had evaporated before close of experiment. 



Cleavage and mitotic figures entirely normal; eggs stain 

 diffusely. 



16-52 cells; cleavage and mitoses approximately normal; 

 eggs are swollen and stain diffusely; deeply staining 

 granules between yolk spheres. 



1 hr. 



16 hrs 



No. 



935 

 936 

 937 

 938 

 939 

 940 

 947 

 948 

 949 

 950 

 951 



952 

 953 



Stage. 



1-2 cells. 



16-24 cells. 



24-30 cells. 



lcell. 



4-12 cells. 



24-30 cells. 



lcell. 



4-12 cells. 



24-30 cells. 



1-16 cells. 



1-16 cells. 



1-16 cells. 

 1-16 cells. 



VII. Effects of Reduced Oxygen Tension. 



1. Sea Water Boiled and Cooled. 



a. In Open Bottles. 



Duration, 



12 hrs. 

 12 hrs. 

 12 hrs. 

 18 hrs. 

 18 hrs. 

 18 hrs. 

 48 hrs. 

 48 hrs. 

 48 hrs. 

 4 hrs. 

 17 hrs. 



24 hrs. 

 40 hrs. 



Normal 



SeaWater. 



Results. 



Ohrs. 

 Ohrs. 

 Ohrs. 

 Ohrs. 

 Ohrs. 

 Ohrs. 

 Ohrs. 

 Ohrs. 

 Ohrs. 

 hrs. 



Ohrs. 

 Ohrs. 



hrs. 16-30 cells, normal 





Ca. 50 cells; normal 

 Ca* 64 cells, normal, 

 25-60 cells, normal. 

 52 cells, normal. 

 64 cells, normal 



1-30 cells: framboisda: fusing eggs; many dead 



• 111 



macromeres : many dead 



52-70 cells; framboisia; isolal 



64-86 cells ; similar to preceding. 



2-20 cells, normal. , 



48-60 cells, nearly normal ; some chromosomes scattered, and 



resting nuclei lobulated or multiple. 



52-70 cells, nearly normal. . 



64-86 cells, nearly normal; sometimes only one blastomere of -J-ceU 



stage develops. _____ 



