Archive image from page 67 of The cyclopædia of anatomy and. The cyclopædia of anatomy and physiology cyclopdiaofana0401todd Year: 1847 46 POLYPIFEUA. the two poles of the balloon becoming ap- proximated, the whole embryo becomes some- what disc-shaped, or the four vessels that communicate with the stomach (if vessels they really are), by moderately contracting, form as many depressions dividing the embryo into four lobes (fig. 50. 5,6.), or by a more forcible contraction give it the appearance of a Greek cross, and all these changes of form may take place in a few seconds. Observations are w
Archive image from page 67 of The cyclopædia of anatomy and. The cyclopædia of anatomy and physiology cyclopdiaofana0401todd Year: 1847 46 POLYPIFEUA. the two poles of the balloon becoming ap- proximated, the whole embryo becomes some- what disc-shaped, or the four vessels that communicate with the stomach (if vessels they really are), by moderately contracting, form as many depressions dividing the embryo into four lobes (fig. 50. 5,6.), or by a more forcible contraction give it the appearance of a Greek cross, and all these changes of form may take place in a few seconds. Observations are wanting relative to the manner in which the free embryo is con- verted into the fixed Tubularia; for although Professor Van Beneden observed the latter at a very early period after they had become at- tached, he was unable to witness the changes that they undergo at the moment of becoming attached to some foreign body, and therefore gives a hypothetical outline of the forms through which he supposes them to pass (Jig. ) preparatory to their final establishment as young Tubulariae (8, 9). Fig. 51. A. series showing the development of Tubularia coro- natafrom ova. 1. A ramification or bud of the ovary. The com- mon cavity continued into it as a cul-de-sac, beyond which is the ovum. 2. The ovum becomes much enlarged, and sur- rounding the cul-de-sac. 3. The cul-de-sac turned aside by gentle com- pression. Indentations on the ovuni indicating the formation of tentacles. 4. An elevation (b) in the centre of the tentacles become perceptible, which afterwards forms the proboscis-like part of the animal. 5. The same compressed between two plates of glass. 6. The embryo after its escape from the ovisac, having as yet but one row of tentacles. 7. The young animal become fixed. The short tentacles beginning to project at the anterior pro- longation or proboscis. Third mode of propagation, by simple ova.— This mode of reproduction approximates the nearest to what occurs in the hi
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