Elementary zoology / by Frank E. Beddard.

  • Beddard, Frank E. (Frank Evers), 1858-1925.
Date:
1911
Catalogue details

Licence: In copyright

Credit: Elementary zoology / by Frank E. Beddard. Source: Wellcome Collection.

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    ectosarc, and the rest of the body within this, again, is made up of a more granular and softer protoplasm, the endosarc. The stalk is seen to contain a central core in the shape of a delicately striated filament; at its attachment to the body, the filament spreads out fan-wise, and forms a layer of ex- cessively fine fibres lying in the ectosarc. This is termed the myophan layer, and is of a muscular nature. It is the muscle in the stalk which enables the contraction already spoken of to be effected. The figure (Fig. 4) shows the layer plainly. The vorticella possesses a contractile vacuole; this undergoes Fig. 5.—Conjugating Vorticella;, highly magnified. (After Maupas.) mac. NU, macronucleus; MIC. nu, micronuclei. regular expansions and contractions. A nucleus is present, which has a horseshoe form, and near it a smaller body, the micronucleus. The large nucleus is termed the niacronuclcus. Like the amoeba, then, the vorticella is a mass of proto- plasm with a nucleus; like the amoeba also, the protoplasm is distinguishable into an outer and inner layer, and there is a contractile vacuole; but in other respects the vorticella is more advanced in structure: the ectoplasm is again subdivided into a outer cuticular and an inner layer, below which again is