CELL DIVISION IN EGGS OF CREPIDULA. 



563 



No. 



995 (1 



(2 



(3 

 (4 



(5 



996(1 



(2 



(3 



(4 



997 (1 



(2 



(3 

 998 (1 



(2 



(3 



999 (1 



(2 

 (3 



(4 

 1,120 (1 



(2 



(3 

 (6 



Stage. 



1-4 cells 



1-4 cells 



1-4 cells 

 1-4 cells. 

 1-4 cells. 



1-2 cells 



1-4 cells 



1-4 cells 

 1-2 cells 

 2-8 cells 

 2-8 cells 



1-4 cells. 

 52 cells. 



52 cells, 



Control. 

 1-4 cells. 



1-4 cells. 

 1-4 cells. 



1-4 cells. 

 1-20 cells. 

 1-20 cells. 



1-20 cells. 

 1-20 cells. 



IV. Effects of Electric Current. 



1. Porcelain-Boot Electrodes, 



Strength. 



i volt (10 dry 

 cells). 



i volt. 



Duration. Normal. 



t 



50min 



li hrs. 



t 



lihrs 

 preceding. 



Beginning control. 



\ volt. 

 J volt. 



End control. 



Control on 997 (2) and (3) . 



15min 



15min. 



1 volt. 



1 volt. 

 4 dry cells. 



4 dry cells. 



12 dry cells. 



12 dry cells. 

 12 dry cells. 



12 dry cells. 

 1 mil. amp, 

 1 mil. amp, 



1 mil. amp, 

 1 mil. amp, 



15min. 



15min. 

 If hrs. 



If hrs. 



Omin. 



Omin. 



Omin 



Jhr. 



2 hrs. 



5 hrs 

 li hrs 



2* hrs 



30min. 

 Omin. 



11 hrs. 



50min. 



|12| hrs. 

 1 J hrs. 



30min. 

 50min. 



50min. 

 45min. 

 45min. 



45min. 

 45min. 



lOmin. 

 40min. 



3 hrs. 

 30min. 

 24 hrs. 



24 hrs. 

 46 hrs. 



Results. 



In eggs most affected spindle fibers are gone 

 and chromosomes fused; in resting nuclei 

 chromatin dissolved. 



Many killed and fragmented; spindle fibers 

 gone, chromosomes fused; nuclei and cyto- 

 ^ plasm dislocated as in centrifuged eggs. 



Similar to preceding. 



Normal 8-16 cell stage. 



Many killed and fragmented; spindle fibers 



gone and chromosomes fused in eggs 

 affected. 



Normal 1-2 cells; many cytasters in egg during 



approach of germ 



2-16 



many normal 



some, nucleus, 



cytoplasm, yolk displaced by convection 

 Similar to preceding. 

 Normal 1-8 cells. 

 Normal 2-8 cells. 



rindle^ fibers gone and chromosomes fused; 

 nuclei, cytoplasm, yolk displaced as in 

 centrifuged eggs. Figs. 88. 89. 91. 



Similar to precedi 



Figs. 80 



Micromeres spherical; cytoplasm collected 

 one side of nucleus. 



mi 



macro- 



Spherical micromeres, separate f 

 meres — framboisia; spindle fibers gone, chro- 

 mosomes fused ; parts dislocated as in centri- 

 fuged eggs. Fig. 93. 



Normal 68-cell stage. 



Nearly normal, few eggs penetrated by current; 



chromatin and cytoplasm stain more faintly 



than in normal eggs. 

 Similar to preceding. 

 Nearly normal; eggs penetrated by current are 



similar to No. 997 (2). 

 Similar to preceding. 

 Quite normal; current too weak. 

 Ca. 52 cells ; generally normal ; large clear nuclei 



in a few eggs ; sphere may be fragmented. 

 Similar to preceding. 

 Ca. 80 cells : quite normal. 



No. 



1,100 

 1,101 



1,102 



1,103 

 1,104 



1,105 



2. Graphite-Plate Electrodes. 

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



Stage. 



2-20 cells 



2 cells 



12-20 cells. 



lfc-20 cells. 

 1-30 cells. 



1-8 cells. 



Strength. 



50 mil. amp. 

 50 mil. amp. 



40 mil. amp. 



40 mil. amp. 

 5 mil. amp. 



5 mil. amp. 



Duration. Normal. 



15min. 

 4min. 



5min. 



5min. 

 5min. 



5min. 



Ohrs. 



17 hrs. 



Ohrs. 



Ohrs. 

 Ohrs. 



Result* 



Eggs coagulated ; polarity unchanged. 



Ca. 25 cells; polarity unchanged; spindles 



normal. . 



Eggs stuck together; no change m 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. Kg. 



68. 

 Similar to preceding. 



