vibracula

In many cases the vibracula have a grooved support at the base, which seems to represent the fixed beak; though this support in some species is quite absent.

VII. Miscellaneous Objections to the Theory of Natural Selection 1909

When a branch was placed on its face, the vibracula became entangled, and they made violent efforts to free themselves.

VII. Miscellaneous Objections to the Theory of Natural Selection 1909

In the avicularia and vibracula of the Polyzoa we have organs widely different in appearance developed from the same source; and with the vibracula we can understand how the successive gradations might have been of service.

VII. Miscellaneous Objections to the Theory of Natural Selection 1909

This view of the development of the vibracula, if trustworthy, is interesting; for supposing that all the species provided with avicularia had become extinct, no one with the most vivid imagination would ever have thought that the vibracula had originally existed as part of an organ, resembling a bird’s head or an irregular box or hood.

VII. Miscellaneous Objections to the Theory of Natural Selection 1909

Besides the avicularia, the Polyzoa possess curious organs called vibracula.

VII. Miscellaneous Objections to the Theory of Natural Selection 1909

Some species are provided with avicularia and vibracula; some with avicularia alone, and a few with vibracula alone.

VII. Miscellaneous Objections to the Theory of Natural Selection 1909

” The avicularia, like the vibracula, probably serve for defence, but they also catch and kill small living animals, which it is believed are afterwards swept by the currents within reach of the tentacula of the zooids.

VII. Miscellaneous Objections to the Theory of Natural Selection 1909

The vibracula may have been directly developed from the lips of the cells, without having passed through the avicularian stage; but it seems more probable that they have passed through this stage, as during the early stages of the transformation, the other parts of the cell with the included zooid could hardly have disappeared at once.

VII. Miscellaneous Objections to the Theory of Natural Selection 1909

In one species examined by me the vibracula were slightly curved and serrated along the outer margin; and all of them on the same polyzoary often moved simultaneously; so that, acting like long oars, they swept a branch rapidly across the object-glass of my microscope.

VII. Miscellaneous Objections to the Theory of Natural Selection 1909