CELL DIVISION IN EGGS OF CREPIDULA. 



565 



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

 2. Graphite-Plate Electrodes. 



No. 



Stage. 



Strength. 



Duration. 



Normal. 



Results. 



1.141 (1) 

 (2) 



1.142 (1) 



(2) 



1-16 cells.* 

 1-16 cells.* 



1-20 cells.* 

 1-20 cells.* 



2 mil. amp. 

 2 mil. amp. 



1 mil. amp. 

 1 mil. amp. 



2 min. 

 2 min. 



5 min. 

 5 min. 



4* hrs. 

 lOhrs. 



4 hrs. 



8hrs. 



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 maeromeres. 



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

 V. Effects of Abnormal Temperature. 



960 



961 (1) 



(2) 



(3) 

 (4) 



1,170 (1) 



(2) 

 1,171 (1) 



(2) 



1.172 (1) 



(2) 



1.173 (1) 



(2) 



1.174 (1) 



(2) 



1-4 cells. 



1-8 cells. 

 1-8 cells. 



1-8 cells. 

 1-8 cells. 



1-2 cells. 



1-2 cells. 

 2-24 cells. 



2-24 cells. 

 1-24 cells. 



1-24 cells. 



2-16 cells, a 

 few gastrulffi. 



2-16 cells. Id. 

 lcell. 



lcell. 



Experiment. 



Ca. 35° C. 



Ca 2°-3° C. 

 Ca 2°-3° C. 



Ca 2°-3° C. 

 Ca 2°-3° C. 



Ca. 38° C. 



f Ca. 38° C. 



1 Ca. 25° C* 



37° C. 



J 37° c. 



I Ca. 25° C* 

 36° C. 



36° C. 



Ca. 23°-25°* 

 37° 



r 37° 



[Ca. 27°< 

 37° 



J 37° 

 I Ca. 27°* 



4 hrs. 



4hrs. 

 16 hrs. 



28 hrs. 

 40 hrs. 



lhr. I 



6 hrs. J 

 Jhr. 



lhr. 1 

 15 hrs. J 



lhr. 



lhr. I 

 15 hrs. J 

 Jhr. 



ihr. 1 

 3 hrs. J 

 ihr. 



ihr. I 

 3 hrs. J 



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. 



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 



Scattered chromosomes of preceding have pro- 

 duced numerous karyomeres. 



Surface tension reduced; mitotic figures very 

 abnormal; spindle fibers gone; chromosomes 

 scattered. 



Scattered chromosomes have produced numerous 

 karyomeres. Fig. 95. 



* Room temperature. 



