. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ARTIFICIAL PARTHENOGENESIS IN PODARKE OBSCURA. 237 amoeboid movement, though, as the egg membrane is closely applied to the surface of the egg, these movements are not as noticeable as in other animals. They were, however, sufficient in amount to make camera drawings impracticable. The pre- served material shows that the cytoplasm is apparently broken up into distinct globules, though from the appearance presented by the living egg I think it altogether probable that they are really in communication with one another, these &
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ARTIFICIAL PARTHENOGENESIS IN PODARKE OBSCURA. 237 amoeboid movement, though, as the egg membrane is closely applied to the surface of the egg, these movements are not as noticeable as in other animals. They were, however, sufficient in amount to make camera drawings impracticable. The pre- served material shows that the cytoplasm is apparently broken up into distinct globules, though from the appearance presented by the living egg I think it altogether probable that they are really in communication with one another, these "globules" be- ing really amoeboid processes. As seen in the drawings, these preparations bear a superficial resemblance to a cleaving egg. There is, however, absolutely no resemblance to the normal cleavage, and a study of the stained material shows that the division is one involving only the cytoplasm, the chromatin being massed together in one of the spheres. This sphere is usually, though not always, larger than the others. (In the egg from which Fig. 3 was drawn, the chromatin, except the small bit seen in one of the upper cells, was in a large cell on the side of the egg opposite that from which the drawing was made.) In the second of the above-de- FIG. 4. " Two-cell" stage. The scribed cases, cleavage involves both nuclear matter is scattered through the cytoplasm. Preserved material. nucleus and cytoplasm. In Fig. 4 several asters are plainly to be seen in each cell, which leads to the suggestion that possibly it is upon the presence or absence of these that the differences in nuclear activity are dependent. Division of these eggs is apparently complete. In the two-cell stage the greatest possible variations in size between the two cells appear, the division being sometimes nearly equal, as in Fig. 4 and again very unequal. I have no reason to believe that this division is karyokinetic. It seems rather as if one of the cells is to be regarded as a lob
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