570 



CELL DIVISION IN EGGS OF CREPIDULA. 



No. 



85S 



859 



870 



871 



872 



873 



874 

 875 



876 



954 

 955 

 956 



IX. Effects of Diluting Sea Wateb with. Fresh Water. 



Stage 



2-4 cells. 



1 part 1 part 



2-4 cells. 



lcell. 

 1-4 cells. 



lcell. 



lcell. 



4-20 cells. 

 1-8 cells. 



4-8 cells 



2-20 cells 

 2-20 cells 

 2-20 cells 



993 (1) 



1-4 cells. 



(2) 



1-4 cells. 



(3) 



1-4 cells. 



1,182 (1) 



1-4 cells. 



(2) 



(3) 



1-4 cells. 



1-4 cells. 



1 



1 



1 



1 



1 



1 

 1 



1 



1 

 1 

 1 



1 



1 



1 



1 



1 



1 



2 



1 

 1 



1 



1 



1 

 2 



2 



1 



1 



1 



1 



1 



1 



1 



1 





Time in 



Dilute. 



1 



2hrs. 



lhr. 



*hr. 

 lhr. 



*hr. 



Jhr. 



lhr. 

 Jhr. 



*hr. 



3 his. 

 3 hrs 

 2 hrs 



If hrs 



lihrs. 



If hrs. 



2hrs. 



Normal 



14hrs. 



Results. 



4hrs. 



1£ hrs. 

 12hrs. 



24-30 cells; yolk cleavage sometimes suppressed, 

 polyasters, multiple nuclei ; chromosomes may be 

 scattered along spindle and form chromatic con- 

 nection between daughter nuclei; older stages 

 normal, or nearly so. Figs. 145, 147, 152, 153. 

 154, 157, 158. 



Many eggs bursted and chromatin of nuclei dis- 

 solved; no separation between yolk and cyto- 

 plasm; chromatic connection between daughter 

 nuclei; nucleoli large. Fig. 141. 



1-2 cells; few abnormalities. 



L— 30 cells; many isolated macromeres showing par- 

 tial cleavage ; blastomeres may be abnormal in size, 

 position and quality; yolk cleavage often sup- 

 pressed ; polyasters and multiple nuclei. Fig. 156. 

 15 hrs. |l-25 cells; cleavage may be adequal and little 



difference between macromeres and micromeres; 

 yolk cleavage increased ; direction of cleavage may 

 be modified ; spindles may be degenerate and con- 

 nective fibers chromatic. Figs. 136, 142, 143. 



Similar to preceding; many eggs fragmented and 



Ca. 52 cells; a few partial eggs, others normal. 

 1-24 cells; isolated macromeres; in some cases yolk 

 cleavage suppressed, in others increased; l T many 



24 hrs 



25 hrs. 

 7hrs 



macromeres 

 m "' 



polyast 



degenerate spindles, 



20 hrs 



Ohrs. 

 14 hrs. 

 36 hrs 





15* hrs 



Ohrs. 



27 hrs. 



yolk; enormous polar body. Figs. 39, 132-ld5, 



137—140 144. 



24-32 cells, many normal, others fragmented; chro- 

 matic connection between daughter nuclei. 



Few eggs, showing few abnormalities. 



Similar to preceding. «k„«mml 



Ca. 68 cells; many show polyasters abnormal 



distribution of chromosomes, multiple nuclei. 



Fin 150 



24^2* cells; in some eggs yolk cleavage suppressed 

 with formation of polyasters, karyomeres, and 

 multiple nuclei ; in others yolk cleavage increased. 



scattered; position and direction of spindles 

 changed 



i. 52 cells ; irregular cleavage ; youc ciea 

 be suppressed, giving rise to polyasters 



nuclei and discoid 



cleavage, or it 



be 



Ohrs. 1-4 



SSS-S: n^rome^s and micromeres becoming 

 AT no'sharp distinction between yoj and 



2 hrs 



18 hrs 



cytoplasm; many yolk spheres ^ ~— « 

 through cell membrane ; lobes and .^P^ 

 at animal pole; large polar bodies, nuclei ia g , 

 centrosomes and spheres smaU and d^, 

 ^tiered chromosomes and karyomeres 



ages 



2 hrs 



28 hrs 



and nuclei displaced and 



macromeres sep'arated. abnormal 



16-52 cells; many normal, ^/Si^s, anc 

 with equatorial and ^^ C JT W ' 



irregular nuclei and ^omeres^ 

 cells; many normal, others similar 



with 

 52-70 



