Journal of experimental zoology . 1-12. Fig. 49. Polar bodies (not shown); groups of chromosome vesicles removed less than a normaldistance from one another; eleven vesicles in each group; abortive cleavage results. Age, sixty-eightminutes. Leitz oc. I (20), obj. i-i2. Fig. 50. Three-celled egg (drawn from three sections). Age, one hour and forty minutes. Leitzoc. I (17), obj. 1-12. Fig. 51. Typical incomplete cleavage. Age, fourteen hours. Leitz oc. i (20), obj. 1-12. Fig. 52. Typical of condition with no cleavage; many nuclei, which vary greatly in size; somevacuoles. Age, twenty hours. Leit
Journal of experimental zoology . 1-12. Fig. 49. Polar bodies (not shown); groups of chromosome vesicles removed less than a normaldistance from one another; eleven vesicles in each group; abortive cleavage results. Age, sixty-eightminutes. Leitz oc. I (20), obj. i-i2. Fig. 50. Three-celled egg (drawn from three sections). Age, one hour and forty minutes. Leitzoc. I (17), obj. 1-12. Fig. 51. Typical incomplete cleavage. Age, fourteen hours. Leitz oc. i (20), obj. 1-12. Fig. 52. Typical of condition with no cleavage; many nuclei, which vary greatly in size; somevacuoles. Age, twenty hours. Leitz oc. i (19), obj. 1-12. Fig. 53. Typical of condition when cleavage is present; few cleavage planes complete; , twenty hours. Leitz oc. i (20), obj. 1-12. Fig. 54. The most advanced and most nearly normal type of cleavage found in my sectionedmaterial; the mesoderm has invaginated; vacuoles present. Age, twenty hours. Leitz oc. I (18)obj. 1-12. PARTHENOGENETIC DEVELOPMENT OF AMPHITRITE. John W. Scott. PLATE IIL 4^. The Jolrnal of Experimental Zoology, Vol. in. Plate IV. Figures of this plate are all from eggs treated with potassium chlorid. Fig. 55. Condition during maturation; one aster present; chromosomes in vesicular conditionand greatly enlarged; no collapse in polar diameter. Age, one hour and thirty-eight minutes. Leitzoc. I (iS), obj. 1-12. Fig. 56. Maturation phenomena; both asters and a faint spindle present; egg did not , one hour and thirty-eight minutes. Leitz oc. i (18), obj. 1-12. Fig. 57. Prophase of first cleavage division. Age, two hours and forty-three minutes. Leitzoc. 3, obj. 1-12. Fig. 58. .•aphase of first cleavage division. Cleavage in such eggs usually abortive. Age,two hours and seventeen minutes. Leitz oc. 3, obj. 1-12. Fig. 59. Telophase of first cleavage divisions; 20 ( + 4?) chromosome vesicle in the right handgroup, 18 ( + 4?) in the left hand group. Cleavage in such eggs is frequently complete. Age, two hoursand twenty
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1904
