CELL DIVISION IN EGGS OF CREPIDULA. 



563 



IV. Effects of Electric Current. 

 1. Porcelain-Boot Electrodes. 



No. 



Stage. 



Strength. 



Duration. 



Normal. 



Kesults. 



995 (1) 



1-4 cells. 



i volt (10 dry 

 cells). 



50 min. 



min. 



In eggs most affected spindle fibers are gone 

 and chromosomes fused; in resting nuclei 

 chromatin dissolved. 



(2) 



1-4 cells. 



i volt. 



ljhrs. 



min. 



Many killed and fragmented; spindle fibers 

 gone, chromosomes fused; nuclei and cyto- 

 plasm dislocated as in centrifuged eggs. 



(3) 



1-4 cells. 



i volt. 



Hhrs. 



Omin. 



Similar to preceding. 



(4) 



1-4 cells. 



Control on preceding. 



1J hrs. 



Normal 8-16 cell stage. 



(5) 



1-4 cells. 



i volt. 



ljhrs. 



fhr. 



Many killed and fragmented; spindle fibers 

 gone and chromosomes fused in eggs most 

 affected. 



996 (1) 



1-2 ceUs. 



Beginning control. 





Normal 1-2 cells; many cytasters in egg during 













approach of germ nuclei. 



(2) 



1-4 cells. 



1 volt. 



15 min. 



2 hrs. 



2-16 cells, many normal; in some, nucleus, 

 cytoplasm, yolk displaced by convection. 



(3) 



1-4 cells. 



i volt. 



15 min. 



5 hrs. 



Similar to preceding. 



(4) 



1-2 ceUs. 



End control. 





ljhrs. 



Normal 1-8 cells. 



997 (1) 



2-8 cells. 



Controlon997(2)and(3). 





Normal 2-8 cells. 



(2) 



2-8 cells. 



1 volt. 



15 min. 



2Jhrs. 



Spindle _ fibers gone and chromosomes fused; 

 nuclei, cytoplasm, yolk displaced as in 

 centrifuged eggs. Figs. 88, 89, 91. 



Similar to preceding. Figs. 80, 81, 85. 



(3) 



1-4 cells. 



1 volt. 



15 min. 



30 min. 



998 (1) 



52 cells. 



4 dry cells. 



1| hrs. 



Omin. 



Micromeres spherical; cytoplasm collected on 

 one side of nucleus. 



(2) 



52 cells. 



4 dry cells. 



If hrs. 



11 hrs. 



Spherical micromeres, separate from macro- 

 meres — framboisia; spindle fibers gone, chro- 

 mosomes fused; parts dislocated as in centri- 

 fuged eggs. Fig. 93. 



(3) 



Control. 







12f hrs. 



Normal 68-cell stage. 



999 (1) 



1-4 cells. 



12 dry cells. 



50 min. 



ljhrs. 



Nearly normal, few eggs penetrated by current; 

 chromatin and cytoplasm stain more faintly 

 than in normal eggs. 



(2) 

 (3) 



1-4 cells. 



12 dry cells. 



30 min. 



10 min. 



Similar to preceding. 



1-4 cells. 



12 dry cells. 



50 min. 



40 min. 



Nearly normal; eggs penetrated by current are 













similar to No. 997 (2). 



(4) 



1-4 cells. 



12 dry cells. 

 1 mil. amp. 



50 min. 



3 hrs. 



Similar to preceding. 



1,120 (1) 



1-20 ceUs. 



45 min. 



30 min. 



Quite normal; current too weak. 



(2) 



1-20 cells. 



1 mil. amp. 



45 min. 



24 hrs. 



Ca. 52 cells; generally normal; large clear nuclei 

 in a few eggs; sphere may be fragmented. 



(3) 



1-20 cells. 



1 mil. amp. 



45 min. 



24 hrs. 



Similar to preceding. 



(6) 



1-20 cells. 



1 mil. amp. 



45 min. 



46 hrs. 



Ca. 80 cells; quite normal. 



2. Graphite-Plate Electrodes. 

 (Eggs of normal control mounted on each slide with those of experiment.) 



No. 



Stage. 



Strength. 



Duration. 



Normal. 



Results. 



1,100 

 1,101 



1,102 



1,103 

 1,104 



1,105 



2-20 cells. 

 2 cells. 



12-20 cells. 



12-20 cells. 

 1-30 cells. 



1-8 cells. 



50 mil. amp. 

 50 mil. amp. 



40 mil. amp. 



40 mil. amp. 

 5 mil. amp. 



5 mil. amp. 



15 min. 



4 min. 



5 min. 



5 min. 

 5 min. 



5 min. 



Ohrs. 

 17 hrs. 



Ohrs. 



Ohrs. 

 Ohrs. 



Ohrs. 



Eggs coagulated; polarity unchanged. 



Ca. 25 cells; polarity unchanged; spindles 



normal. 

 Eggs stuck together; no change in nuclei or 



spindle. 

 Similar to preceding. 

 Many eggs ruptured, blastomeres isolated, 



exovates due to pressure; polar rays and 



spindle fibers may be faint or lacking. Fig. 



68. 

 Similar to preceding. 



