42 O EDWIN G. CONKLIN. 



EXPLANATION OF PLATE II. 



FIG. 7. No. 960. Ca. 35, 4 hrs., during third cleavage. The chromosomes 

 have scattered and formed numerous chromosomal vesicles. 



FIG. 8. No. 1176(2). 34-35, i hr., during anaphase of third cleavage; 

 room temperature (ca. 23) 3 hrs. Many nuclei are lobed or irregular; nuclei are 

 most abnormal in the quadrant in which a micromere did not form, and in which 

 mitosis was not so far advanced at the time of the experiment, as in the other 

 quadrants. 



FIG. 9. No. 1176(1). 34 35, j hr., during fourth cleavage of macromeres. 

 In three quadrants the chromosomes are scattered in the spindles, in the fourth 

 are chromosomal vesicles. The nuclei and centrosomes in the first set of micro- 

 meres are in a resting stage and are absolutely normal. 



FIG. 10. No. 1176(1). 34-35, J hr., during fourth cleavage. Chromosomal 

 vesicles are present in one of the macromeres, and chromosomes are more or less 

 scattered in all micromeres of the first set. 



FIG. n. No. 1176(2). 34-35, 5 hr., during fourth cleavage; room tempera- 

 ture (23) 3 hrs. The nuclei formed after the division of the first set of micro- 

 meres are lobed and irregular; the scattered chromosomes in the macromeres 

 have formed many karyomeres. This figure shows an egg like Fig. 9 after being 

 kept three hours at normal temperature. 



FIG. 12. Same slide as preceding. Many lobulated nuclei and karyomeres 

 in the cells derived from the first set of micromeres; nuclei in second set of micro- 

 meres and in macromeres are nearly normal. This figure shows an egg like Fig. 

 10, after being kept three hours at normal temperature. 



