. The Protozoa. Protozoa. Fig. 115. — Ciliata with tentacles. A. Ileonema dispar Stokes. [Stokes.] B. Mesodinium pulex Clap, and Lach. [Entz.] C. Hypocoma parasitica Grub. [Engelmann.] t, tentacles. direct connection between the tentacles of the two groups, but regarded them as independent adaptations. The hypothesis advanced by Butschli is that primitive forms of Suctoria (such as Hypocoma (C), which has but one suctorial tentacle, and which retains its cilia throughout life, the cilia being upon the ventral side only, as in hypotrichous forms of Ciliata) were derived from hypotrichous ciliat
. The Protozoa. Protozoa. Fig. 115. — Ciliata with tentacles. A. Ileonema dispar Stokes. [Stokes.] B. Mesodinium pulex Clap, and Lach. [Entz.] C. Hypocoma parasitica Grub. [Engelmann.] t, tentacles. direct connection between the tentacles of the two groups, but regarded them as independent adaptations. The hypothesis advanced by Butschli is that primitive forms of Suctoria (such as Hypocoma (C), which has but one suctorial tentacle, and which retains its cilia throughout life, the cilia being upon the ventral side only, as in hypotrichous forms of Ciliata) were derived from hypotrichous ciliates by the mouth portion becoming progressively drawn out into a tentacle. Haeckel ('96), adopting Biitschli's view, compared the simple, single, and terminal mouth-tube of a primitive suctorian with the long, proboscis-like oral region of certain holotrichous ciliates, such as Lacrymaria olar or L. phcenicopterus. In the closely allied forms, Didinium and Mesodinium, the oral tube is not ciliated and is contractile, so that when food is taken in, the tube widens into more or less of a disk similar to many suctorian tentacles. In Mesodinium,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Calkins, Gary N. (Gary Nathan), b. 1869. New York, The Macmillan company; London, Mamcillan & co. , ltd.
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