Identifier: introductiontozo00dave Title:
Introduction to zoology; a guide to the study of animals, for the use of secondary schools; Year:
1900 (
1900s) Authors:
Davenport, Charles Benedict, 1866-1944 Davenport, Gertrude Anna Crotty, 1866- Subjects:
Zoology Publisher:
New York, Macmillan company London, Macmillian and co., ltd. Contributing Library:
MBLWHOI Library Digitizing Sponsor:
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view book online to see this illustration in context in a browseable online version of this book. Text Appearing Before Image: FIG. 140. — Serpula tube on a bit of oystershell that is perforated by the boring sponge.The tube lies in the centre of the figure.Nat. size. Photo, by W. H. C. P. 152 ZOOLOGY B Text Appearing After Image: FIG. 141. — Trichina. A, encysted form in muscle of pork; B, female; C, male; bh, envelope of cyst; cy, cyst; de, male duct; e, embryos; /, fatglobules; h, testis; mf, muscle fibre; oe, pharynx; ov, ovary; no, openingto egg duct; zh, cell masses in intestines. After Clans. NEREIS AND ITS ALLIES 153 T) pin-worm of man. Others still penetrate into the mus-cles, and cause great pain and often death. Such is thepork-worm, Trichina,1 which gets into man through un-cooked pork, multiplies in thefood canal, migrates in greatnumbers into the muscles andencysts itself there (Fig. 141).Another group which islargely parasitic is that of theflatworms. Some flatwormslive free in ponds. They willbe found abundantly amongplants taken from small pondsin the summer and autumn, andare commonly known as Pla-naria2 (Fig. 142). They maybe recognized not only by theirflattened form, but also by acurious proboscis which pro-trudes from the middle of theunder side of the body and bears «/ mouth at its tip. Note About Images 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 work.