| Description |
: |
The organization and cell-lineage of the ascidian egg / by Edwin G. Conklin.
Figs. 13 and 14. Side views of egg, showing the formation of the crescent (cr.) from the yellow hemisphere ; in all the figures the animal pole is above, the vegetal pole below. Above the yellow crescent is an area of clear protoplasm (c. p.).
Fig. 15. Similar stage of another egg showing the aggregation of test cells over the crescent and the protrusion of the chorion at this place, an unusual phenomenon.
Fig. 16. Egg showing crescent, viewed nearly from the vegetal pule
Fig. 17. Another egg showing crescent and clear protoplasm, viewed from posterior pole; the animal pole is above, the vegetal below.
Figs. 18, 19, 20. Successive stages of the same egg drawn at intervals of about two minutes, showing the approaching division of the egg.
Figs. 21, 22, 23, 24. Succesive stages in the first cleavage of an egg, drawn at intervals of about two or three minutes. The egg is viewed from the posterior pole and shows the complicated forms taken by the yellow crescent during the division, also the enlargement of the area of clear protoplasm and its extension toward the animal pole. |
