. Elementary text-book of zoology [electronic resource]. Zoology. PL A T YHELMINTHES. The life-history may be illustrated diagrammatically : — PHYLUM PLATYHELMINTHES. The Platyhelminthes, or flat-worms, form a well- defined group of the affinities of which little is known. The two types given, Distomum and TcE?iia, represent the two " parasitic" classes of the phylum. 1. Trematoda.—The Trematoda are all parasites, the Monogenea are mostly ectoparasites with one host, and the Digenea are endoparasites with two hosts. 2. Cestoda.—The Cestoda illustrate enteric parasitism with entire lo
. Elementary text-book of zoology [electronic resource]. Zoology. PL A T YHELMINTHES. The life-history may be illustrated diagrammatically : — PHYLUM PLATYHELMINTHES. The Platyhelminthes, or flat-worms, form a well- defined group of the affinities of which little is known. The two types given, Distomum and TcE?iia, represent the two " parasitic" classes of the phylum. 1. Trematoda.—The Trematoda are all parasites, the Monogenea are mostly ectoparasites with one host, and the Digenea are endoparasites with two hosts. 2. Cestoda.—The Cestoda illustrate enteric parasitism with entire loss of alimentary canal. They usually alternate between two hosts and show a cestoid and cystic stage. Tcenia saginata is a common type found in the ox and man. It has no hooks and is larger than TcEJiia solium. In these the cystic stage has only one head and is called a cysticejrus, but in some, such as TcEiiia CLvniiriis, alternating between the dog (cestoid) and sheep (cystic), the cystic itage has many heads and is called a Ccvnurus. It produces "sheep-gid" or " sturdy " by pressure on the brain. Another small tape- worm of the dogs, Tcenia echinococci^ has enormous cysts, with secondary cysts and many "heads " {Echinococci), which may occur in man, sheep or pigs. The members of the third class, or Turbeilaria, are not parasites, but are terrestrial, marine, or freshwater. In a number of characters they resemble the other classes. The body is usually flattened dorso-ventrally. There is S cole X. Proglottis. 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 Masterman, Arthur Thomas; Parsons, John Herbert, Sir, 1868-1957, donor; S. H. Lazarus (Firm); University College, London. Library Services. Edinburgh : E. & S. Livingstone
Size: 2411px × 1037px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1901
