CELL DIVISION IN EGGS OF CREPIDULA. 



565 



IV* Effects of Electric Current. — {Continued.) 



2. Graphite-Plate Electrodes. 



No. 



Stage. 



Strength. 



1,141 (1) 



(2) 



1,142 (1) 



(2) 



*! 



1-16 cells.* 2 mil. amp 



1-16 cells.* 



2 mil. amp 



1-20 cells.* 



1-20 cells. 



1 mil. amp 



1 mil. amp 



Duration. 



Normal. 



2 min. 



4£ hrs. 



2 min. 



lOhrs. 



5 min. 



4 hrs. 



5 min* 



8 hrs. 



Results. 



1 



-29 cells ; many fragmented eggs showing par- 

 tial cleavage; chromatic granules scattered 

 throughout the yolk. 

 20-48 cells (a few older) ; eggs generally normal ; 

 some isolated blastomeres showing partial 



cleavage; many lobulated nuclei and karyo- 

 meres. 



1-20 cells; many eggs fragmented, others fused 

 together; cytoplasm not segregated from 

 yolk; chromatin may be dissolved. 



1-29 cells; many normal, others similar to 

 preceding; yolk cleavage may be suppressed, 

 with formation of polyasters, or increased, 

 with formation of many macromeres. 



Water carefully drained off graphite plate; contact through eggs and egg capsules only. 



V. Effects of Abnormal Temperature. 



No. 



Stage. 



960 





961 (1) 



(2) 



(3) 

 (4) 



1,170 (1) 



1-4 cells 



1-8 cells 

 1-8 cells 



1-8 cells 



1-8 cells. 



Experiment. 



Ca. 35° C. 



Ca 2°-3° C 

 Ca 2°-3° C 



Ca 2°-3° C 



Ca 2°-3° C 



i 



1-2 cells 



(2) 

 1,171 (1) 



1-2 cells. 

 2-24 cells. 



Ca. 38° C. 



J Ca. 38° C. 

 \ Ca. 25° C* 



37° C. 



(2) 

 1,172 (1) 



2-24 cells 



1-24 cells 



(2) 

 1,173 (1) 



1-24 cells. 



2-16 cells, a 

 few gastrulse. 



37° C. 

 Ca. 25° C* 



36° C. 



(2) 2-16 cells. Id 



1,174 (1) 



(2) 



lcell. 



lcell. 



Ca 



36° C. 

 23°-25°* 

 37° 



37 

 Ca. 27°* 

 37° 



ICa.' 



37° 

 27 



o* 



* Room temperature. 



Duration. 



Results. 



4 hrs. 



4 hrs. 

 16 hrs. 



28 hrs. 



lhr. 



lhr. 

 6 hrs 

 ihr. 





Eggs degenerating; chromatin of resting nuclei 

 clumped; chromosomal vesicles scattered; cyto- 

 plasm vacuolated. 



1-8 cells, normal. 



4-8 cells, normal; spheres very distinct. Figs. 



100-102. 



8-16 cells, normal; spheres very distinct with pe- 

 ripheral layer of coarse granules. 

 40 hrs. |4-30 cells; polyasters and multiple nuclei in cells 



where cleavage furrow was suppressed; sphere 

 less distinct, and sphere granules scattered. 

 Figs. 103-105. 



Surface tension reduced; eggs very irregular in 

 outline, with all archiplasm drawn into central 

 area or in small masses under cell membrane; 

 no astral rays or spindle fibers; chromosomes 

 scattered. Fig. 94. 



Similar to preceding; no development. 



Profound changes in structure and orientation of 

 mitotic figures; chromosomes scattered; cen- 

 trosomes and spindle fibers gone; archiplasm 

 drawn into astral areas, or collected along 

 division walls. Figs. 96, 97. 



Similar to preceding; chromosomes do not form 

 nuclei and may be far away from cytoplasmic 

 areas. Figs. 98, 99. 



Similar to 1,171 (1); archiplasm very distinct from 

 surrounding plasma. 



Similar to 1,171 (2). 



Surface tension reduced; spindle fibers gone; 

 chromosomes scattered ; archiplasm not sharply 



segregated. 



Scattered chromosomes of preceding nave pro- 

 duced numerous karyomeres. 



Surface tension reduced; mitotic figures very 

 abnormal; spindle fibers gone; chromosomes 



scattered. 

 Scattered chromosomes have produced numerous 



karyomeres. Fig. 95. 



ihr. 

 15 hrs 



lhr. 



lhr. 



15 hrs 



}hr. 



Jhr. 

 3 hrs 

 ihr. 



thr. 

 3 hrs 



