The main points in the foregoing paper maybe summarised as follows :

(1) A "yolk nucleus" of the type described by Bambeke, as occurring in the egg of Pholcus, is present in the developing egg of Flustrella hispida.

(2) Segmentation and cell-lineage have been followed out in detail up to the 32-cell stage.

(3) The formation of the endoderm has been traced.

(4) The oral and aboral ectoderm are differentiated as early as the 16-cell stage, and remain quite distinct from that time onwards.

(5) The ciliated ring of the larva is formed by the coalescence of several originally distinct rows of cells, and not by the hypertrophy of a single row.

(6) A stomach, comparable to that of Alcyonidium, is present also in Flustrella.

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