The inspection of meats for animal parasites / prepared under the direction of D.E. Salmon.

Date:
1898
Catalogue details

Licence: Public Domain Mark

Credit: The inspection of meats for animal parasites / prepared under the direction of D.E. Salmon. Source: Wellcome Collection.

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    longer than broad; testicles usually arranged in two triangles; eggs 52 to 60 u, bulb of pyriform body 20 to 24 /i, horns 12 to 15 /1. The Triangle Moniezia (M. trigonophora), p. 128. Stilesia. (24) Slrobila transparent, whitish or grayish yellow, 45 to 60 mm. long, not over 2.5 mm. broad; head 0.5 to 1 mm. broad ; median portion of median field transparent; two lateral cornucopia-like egg pouches present in each segment. The Globipunctate Tapeworm (S. globipunctata), p. 130. Strobila attains nearly 3 meters in length, but not over 3 mm. in breadth; head 1.5 to 2 mm. broad; median field occupied by transverse uterus. The Centripunctate Tapeworm (S. centripunctata), p. 130. FLUKES, OR TREMATODES (Order Trematoda). The following technical description shows the systematic position and general structure of the flukes under discussion: [Suborder Malacocotylea: Digenea. Families Fasciolidae and Amphistomidae. See figs. 3, 29, 30, 37, 41, 42, 43, and 50.] With the exception of the Blood Flukes (Schistosoma), they are all hermaphrodites. They are flat or conical worms, always longer than broad; on the anterior extremity is situated the mouth, surrounded by a muscular organ, known as the oral sucker and curved slightly ventrad. There is a second sucker (the acetabulum), which is situated in the median ventral line; in the Fasciolidae the acetabulum is generally found on the anterior half of the body, Avhile in the family Amphistomidae it is at or near the posterior extremity. The surface of the worms is generally more or less covered with minute spines, or tubercles. The digestive tract consists of the mouth, a short oesophagus, and two blind sacs (intestinal caeca), which represent the true intestine. The anterior portion of the oesophagus is generally connected with the mouth by a muscular bulb (the pharynx); the posterior extremity bifurcates, one branch being connected with each intestinal caecum. The intestinal sacs are usually simple elongated tubes, but in the genus Fasciola they branch freely (fig. 29). In Schistosoma the two caeca unite after pass- ing the acetabhlum. An anus is never present. Genital organs.—The genital pore is in the ventral median line in all species here de- scribed, the male copulatory organ (cirrus or penis) lying very close to the female open- ing (vulva). Male organs: A cirrus is frequently seen extruded from the genital pore, and in those cases it appears as a curved organ, varying in size according to the spe- cies; usually the cirrus is invaginated in the cirrus pouch. Through its center runs a canal (the ductus ejaculatorius) which receives the spermatozoa from a vesicula semi- nalis. The latter is partially or entirely included in the pouch; at its posterior end 5t receives the two vasa deferentia, through which the spermatozoa are con- ducted from the testicles. The testicles, generally two in number, one right and one left, are more or less round, lobed, or branched. Female organs: The vulva leads into a canal, the anterior portion of which is known as the metraterm; this is con- tinued as the uterus, which forms more or less numerous folds in the median portion of the body and finally leads to the so-called shell-gland which may frequently be seen in fresh specimens (F. magna and others) as a round body a short distance pos- terior of the acetabulum. In the center of the shell gland is a canal (the ootyp), in which four canals (uterus, oviduct, Laurer’s canal, and vitello-duct) come together. The ovary in some species is globular, in others branched, and connects with the ootyp through the oviduct. The Laurer’s canal runs from the ootyp dorsad in curves and opens to the exterior on the dorsal surface; its function is still doubtful, but