Part 10

SPECIFIC DIAGNOSIS.—_Hymenolepis_: Strobila 10 to 60 millimeters in length, 2.5 to 4 millimeters in maximum breadth; composed of 800 to 1,300 segments. Head small, almost globular; 200 to 600μ in width; rostellum rudimentary, pyriform, only slightly protractile; hooks absent; suckers globular, near the apical portion of the head, 80 to 160μ in diameter. Neck usually short. Segments throughout strobila broader than long. Genital pores on left margin, near the junction of the anterior and middle thirds of each segment. Three testes in each segment; vas deferens dilates into a prominent seminal vesicle before entering the cirrus pouch, within which also is a vesicle. Gravid uterus occupies most of the proglottids; its cavity is subdivided into a large number of incompletely separated compartments filled with eggs. Eggs round or slightly oval; outer membrane 54 to 86μ in diameter, yellowish in color, may be radially striated; inner membrane 24 by 20μ to 40 by 35μ in diameter, with mammillate projection at each pole often not apparent; between outer and inner membranes a prominent third layer of albuminous substance, often appearing as two delicate smooth membranes, with intervening space filled by a granular coagulum; embryonal hooks 11 to 16μ in length.

[Illustration:

FIG. 27.—Male and female organs of _H. diminuta_: _c. p._, cirrus pouch; _g. p._, genital pore; _ov._, ovary; _rec. sem._, receptaculum seminis; _s. g._, shell gland; _t._, testiculæ; _ut._, uterus; _vag._, vagina; _v. def._, vas deferens; _v. ef._, vas efferens; _ves. sem._, vesicula seminalis; _y. g._, yolk gland. Enlarged. (After Zschokke, 1889, pl. 2, fig. 22.) ]

[Illustration:

FIG. 28.—Gravid segment of _H. diminuta_. Enlarged. (After Grassi, 1881, pl. 11, fig. 15.) ]

[Illustration:

FIG. 29.—Egg of _H. diminuta_ from man. Greatly enlarged. (After Bizzozero, 1889a, pl. 4, fig. g″.) ]

HABITAT.—Adults in small intestine of brown or Norway rat (_Mus decumanus_), black rat (_M. rattus_), house mouse (_M. musculus_), Egyptian or roof rat (_M. rattus alexandrinus_), wood or field mouse (_M. sylvaticus_), _Rhipidomys pyrrhorhinus_ [according to Linstow, 1878a, 23], and man (_Homo sapiens_).

DEVELOPMENT.—The larval stage (_Cercocystis H. diminutæ_) occurs in larval and adult meal moths (_Asopia farinalis_); in young and adult earwigs (_Anisolabis annulipes_); and in adult beetles (_Acis spinosa_ and _Scaurus striatus_).

GEOGRAPHIC DISTRIBUTION.—Massachusetts, Pennsylvania, Nebraska, Iowa, District of Columbia, Maryland, Brazil, Italy, Germany, France, Austria.

This parasite is certainly more common in man in this country than has heretofore been assumed, but fortunately it seems to be one of the most harmless and most easily expelled tapeworms occurring in man.

[Illustration:

FIG. 30.—Encysted cystic stage of _H. diminuta_: _caud._, caudal appendage; _cyst._, adventitious capsule inclosing the cercocystis. Enlarged. (After Grassi & Rovelli, 1892a, pl. 4, fig. 1.) ]

From present evidence, the rats and mice are looked upon as the regular hosts for this worm, and hence as the natural reservoir of the infection. The intermediate host becomes infected from the rodents and then transmits the infection to man.

It might be mentioned that as yet no extensive study has been conducted in the United States to differentiate clearly the various species of _Hymenolepis_ found in our rats and mice. The possibility is therefore not entirely excluded that some of our cases of _Hymenolepis diminuta_ may eventually be shown to be referable to other species of the same genus.

NEMATODA—TRUE ROUND WORMS.

Family TRICHINELLIDÆ.[AA]

Footnote AA:

SYNONYM.—_Trichotrachelidæ._ It becomes necessary under the international code to change the family name; the family name _Trichinellidæ_ is chosen as less likely to lead to confusion than a family name based upon _Trichuris_.

FAMILY DIAGNOSIS.—_Nematoda_: Elongate cylindrical worms; cephalic portion long and very slender, caudal portion more or less swollen. Mouth rounded, without lips. Esophagus relatively very long, composed of a single row of large cells, forming the so-called “cell body” and supporting a narrow esophageal tube; anus terminal or nearly so.

Male: With a single spicule or without spicule.

Female: With one ovary; vulva near caudal end of cell body, close to point where body increases in diameter; oviparous or viviparous.

Eggs: Oviparous species, with thick shell, with opening at each pole, closed by a transparent plug.

TYPE GENUS.—_Trichinella_ Railliet, 1895.

This family furnishes two parasites to man: The whipworm (_Trichuris trichiura_) of the colon, and the trichina or flesh worm (_Trichinella spiralis_, see p. 101).

Genus TRICHINELLA[AB] Railliet, 1895.

Footnote AB:

SYNONYMS.—_Trichina_ Owen, 1835 [not Meig., 1830, insect.]; _Trichinus_ Fraser, 1881a, for _Trichina_.

GENERIC DIAGNOSIS.—_Trichinellidæ_: Very minute worms, of nearly uniform diameter. Adults in intestine of mammals, larvæ encysted in muscles.

Male: Without spicules, but with 2 conical appendages on the tail, at side of terminal cloacal opening.

Female: Vulva about one-fifth the length from anterior end; viviparous.

TYPE SPECIES.—_Trichinella spiralis_ (Owen, 1835) Railliet, 1895.

TRICHINELLA SPIRALIS (Owen, 1835) Railliet, 1895.

[Figs. 31 to 51.]

SPECIFIC DIAGNOSIS.—_Trichinella_: Body thread-like, visible to naked eye.

Male: Length, 1.4 to 1.6 millimeters; diameter, 40μ; distal of cloacal opening, 2 pairs of papillæ, the anterior pair hemispherical, posterior pair conical.

Female: Length, 3 to 4 millimeters; diameter, 60μ; anus terminal; vulva one-fifth of length of body from the mouth; viviparous.

HABITAT.—Adults in lumen and wall of small intestine, encysted larvæ in muscles of various mammals, particularly in rats, mice, swine, and man.

GEOGRAPHIC DISTRIBUTION.—More or less cosmopolitan.

SOURCE OF INFECTION.—From the life cycle of this parasite it is clear that the permanent reservoir of infection must be some animal with cannibalistic tendencies. Of the three most important hosts (man, swine, and rats), the rats present ideal conditions in this respect. It is true that there are some tribes of man which are cannibalistic, but their distribution is restricted. Likewise swine are in so far cannibalistic that they eat uncooked swine offal and swill, but this is due to the shortsightedness of man rather than to the habits of the swine. Accordingly, neither man nor the hog presents the proper theoretical conditions for the perpetuation of the parasites and hence to serve as reservoir for the disease it causes.

Rats, on the contrary, are cannibalistic, and trichinosis is a common disease among them. Hence they may be viewed as the natural reservoir for the parasites and for the disease it causes; hence, also, any well-directed public health campaign against trichinosis should consider the eradication of rats.

Rats become infected by eating each other; by eating scraps of pork found on the offal pile of slaughterhouses, or in swill; and by eating scraps of human flesh in dissecting rooms of medical schools.

[Illustration:

FIG. 31.—Female trichina from the intestine; 24 hours after infection. Enlarged. (After Leuckart, 1866a, pl. 1, fig. 1.) ]

Swine become infected by eating rats, and by eating scraps of pork on the offal pile of slaughterhouses, or in swill.

Man becomes infected almost exclusively by eating pork and boar meat. The rare infections which occur from eating other meat are almost negligible.

MEDICAL SIGNIFICANCE.—_Trichiniasis_ or _trichinosis_ refers to infection with the trichina or flesh worm. Normally it occurs only in mammals, chiefly carnivorous and omnivorous species, and it is transmissible from any infected mammal to any other mammal susceptible to it, in case the latter eats the uncooked flesh of the former.

_Symptoms._—In heavy infections there may be three more or less distinct periods of the disease, corresponding to the three stages in the life cycle of the parasite; but these stages are obscure in light or in repeated infections. Profuse sweating may last during the entire attack.

[Illustration:

FIG. 32.—Gravid adult female trichina. Enlarged. (After Leuckart, 1866a, pl. 1, fig. 2.)

FIG. 33.—Adult male trichina from the intestine. Enlarged. (After Leuckart, 1866a, pl. 1, fig. 5.)

FIG. 34.—External genitalia of same. Enlarged. (After Leuckart, 1866a, pl. 1, fig. 7.)

FIG. 35.—The same with extruded cloaca. Enlarged. (After Leuckart, 1866a, pl. 1, fig. 8.)

FIG. 36.—Cephalic portion of a trichina showing central nervous system and anterior portion of intestinal canal. Greatly enlarged. (After Leuckart, 1866a, pl. 1, fig. 13.)

FIG. 37.—Transverse section of a female trichina. Greatly enlarged. (After Leuckart, 1866a, pl. 1, fig. 16.)

FIG. 38.—Young trichina embryo in a muscle fibre. Greatly enlarged. (After Leuckart, 1866a, pl. 2, fig. 1.) ]

Period of ingression: The adult parasites are in the intestine, hence gastro-intestinal symptoms develop; irregular appetite, nausea, diarrhea or constipation, colicky pains; a temporary edema around eyes about the eighth day; muscular pains begin.

Period of digression: This begins about the eighth to the fifteenth day, sometimes later; young embryos are wandering to and attacking the muscles, hence muscular symptoms (myositis) develop; painful tension of muscles, especially biceps; members assume semiflexed position; movements, chewing, swallowing, breathing, and speech become difficult; eyes become fixed; fever.

[Illustration:

FIGS. 39–42.—Later stages of same; the muscular structure is undergoing changes. (After Leuckart, 1866a, pl. 2, figs. 3, 6, 7, 8.)

FIGS. 43–45.—Muscle trichinæ, 0.3 mm., 0.4 mm., and 0.6 mm. long. (After Leuckart, 1866a, pl. 2, figs. 10–12.) ]

Period of regression: The parasites become encysted in muscles. All symptoms may increase, then gradually decrease; cachexia and anemia resulting from malnutrition; pruritis, miliary cutaneous eruptions; desquamation; about twenty-fourth day, a “second” edema develops, especially about the face; lungs may become edematous; bronchial catarrh, pneumonia, or pleurisy may appear; gradual recovery.

[Illustration:

FIG. 46.—A female trichina from the muscle. Greatly enlarged. (After Leuckart, 1866a, pl. 1, fig. 12.) ]

[Illustration:

FIG. 47.—A piece of pork with encysted trichinæ. Enlarged. (After Braun, 1903, p. 251, fig. 195.) ]

_Lethality._—The lethality varies from 0 to 100 per cent; it averaged 5.6 per cent in 14,820 cases collected from literature; it is dependent upon amount of infection which remains in the body; low before second and after seventh week, highest from fourth to sixth week.

_Prognosis._—Better in cases having severe diarrhea in first stage.

_Complications and sequelæ._—Abortion, menstrual disturbances, pneumonia, pleurisy, peritonitis.

[Illustration:

FIG. 48.—Section through a rat’s muscle; the infected muscle fiber has lost its striation, its nuclei are enlarged and increased in number. Greatly enlarged. (After Hertwig-Graham, see Braun, 1903, p. 284, fig. 212B.)

FIG. 49.—Portion of an isolated trichina cyst, at the pole of which connective tissue cells have wandered into the thickened sarcolemma. Greatly enlarged. (After Hertwig-Graham, see Braun, 1903, p. 284, fig. 212C.) ]

_Clinical diagnosis._—Make microscopic examination:

(1) Of pork, if any has been left, to find encysted larvæ; if larvæ are found, feed pork immediately to two or three guinea pigs or _white_ rats, to determine if the encysted larvæ are alive; kill one rat after three days and examine intestinal content for adult; kill the second rat after two weeks, the third rat after three weeks, and hunt for larvæ in muscular portion of diaphragm. Even if live trichinæ are found in intestine, an examination of the muscles may show that the worms were too weak to reproduce, hence prognosis is favorable.

(2) Of patient’s blood, for increased proportion of eosinophiles.

(3) Of patient’s stools, for discharged adult worms, especially if diarrhea is severe; dilute the fecal matter with warm water and pour off whatever floats; place remainder in a shallow glass dish so that it will not be over one-twelfth of an inch deep; move the dish gently around over a dark background (such as dark paper), and hunt for small hair-like objects; place these, if found, in a drop of water on a slide, cover with a cover slip, and examine under low power. Or, if necessary, make a microscopic examination.

(4) Of small excised portion of patient’s deltoid, about three to four weeks after infection, for encysted larvæ; cut a small piece parallel to muscle fibers, tease this on a slide, add a drop of pure water, or water and glycerine, cover with another slide, flatten gently by pressure while examining under low power.

[Illustration:

FIG. 50.—Calcified trichinæ in uncalcified cysts, from pork. Enlarged. (After Ostertag, see Braun, 1903, p. 285, fig. 213.) ]

Suspect trichinosis especially under following circumstances: Several patients in same family or in same neighborhood, usually of North German descent, show typhoid-like symptoms shortly after a celebration (wedding, birthday party, etc.) at which pork was served.

[Illustration:

FIG. 51.—Three phases of calcification of trichinæ and their cysts, the changes starting from the poles of the cysts. Enlarged. (After Ostertag, see Braun, 1903, p. 285, fig. 214.) ]

_Differential diagnosis._—Consider especially typhoid fever and rheumatism.

_Treatment._—Purge in early stage to carry away the adult worms and thus eventually decrease the amount of muscular infection. No treatment is known which can be relied upon to kill the larvæ in the muscles; benzine has been suggested. Stimulants may be given to carry patients through until the larvæ encyst.

PROPHYLAXIS.—_Kill off rats and mice._—Educate public to eat pork only when thoroughly cooked or thoroughly cured. A practical test of cooking is the white color of the meat on being cut; if the cut surface is reddish and serous, the pork is not sufficiently cooked to kill trichinæ.

As a matter of practical experience, the microscopic inspection of pork has not given the protection it is generally supposed to give. Of 6,329 cases with 318 deaths reported for Germany during the years 1881–1898, 3,388 cases with 132 deaths are directly attributable to faults in the inspection. This system directly increases the tendency to eat raw pork, gives the public a false sense of security, and does not give practical results commensurate with its expense.

ACANTHOCEPHALA—THORN-HEADED WORMS.

Genus GIGANTORHYNCHUS Hamann, 1892.

GENERIC DIAGNOSIS.—_Acanthocephala, Gigantorhynchidæ_: Large worms with annulate round to flat, tape-like body. Hooks with 2 roots and completely covered with transparent chitin. Proboscis sheath a muscular apparatus, without cavity. Central nervous system caudad of equator of proboscis sheath and eccentric. Lemnisci long, cylindrical, with central canal.

TYPE SPECIES.—_Gigantorhynchus echinodiscus_ (Diesing, 1851).

The Moniliform Thorn-headed Worm—GIGANTORHYNCHUS MONILIFORMIS

(Bremser, 1819).

[Figs. 52 to 58.]

SPECIFIC DIAGNOSIS.—_Gigantorhynchus_ (p. 108): Body attenuated anteriorly, with fine transverse striæ or rings, or even constrictions which give the appearance of a series of beads, except in the caudal fourth of body, which is nearly smooth and cylindrical. Proboscis 425 to 450μ long, 176 to 190μ in diameter, armed with feeble, very curved, 26μ long, hooks arranged more or less in quincunx and forming at most 15 transverse and about 12 longitudinal rows. Lemnisci more than a centimeter in length, cylindrical, undulated posteriorly.

Male: Length 4 to 4.5 centimeters long; bursa campaniform.

Female: Length 7 to 8 centimeters (to 27 centimeters after Westrumb).

Eggs: Ellipsoidal, 85 by 45μ; external envelope thin, yellowish; middle envelope very thick, colorless, homogeneous; inner envelope less thick, colorless, and quite pliant. Embryo striated transversely in posterior two-thirds, and covered with spines which increase in size toward anterior end of embryo, the anterior spines being transformed into hooklets with prong and base.

Development: With beetles (_Blaps mucronata_) as intermediate host.

HABITAT.—Small intestine of various small mammals; brown rat (_Mus decumanus_); white rat (_Mus norvegicus albus_); _M. fuscirostris_; hamster (_Cricetus frumentarius_); dormice (_Myoxus quercinus_ or _glis_); field mole (_Arvicola arvalis_ or _agrestris_?); _Lemnus arvalis_; and _Mustela putorius_. It can also develop in man, as has been shown experimentally by Grassi and Calandruccio (1888, 521–525).

MEDICAL SIGNIFICANCE.—Grassi and Calandruccio report a doubtful case of infection in a girl near Catania. Calandruccio infected himself experimentally by swallowing the young worms taken from a Blaps. Twenty days later he was seized with severe pains which increased on pressure; diarrhea followed, with ringing in the ears, fatigue, and somnolence. Seventeen days later the characteristic eggs were found in his stools, and twelve days later the symptoms became so severe that he took 8 grams of extract of male fern; one to two hours later he passed 53 of the parasites. For two days the symptoms continued, on the second day fever developed, but all symptoms disappeared on the third day.

[Illustration:

FIG. 52.—_Gigantorhynchus moniliformis_, female. ×2. (After Grassi & Calandruccio, 1888, p. 523, fig. 1.)

FIG. 53.—_G. moniliformis_, male. ×2. (After Grassi & Calandruccio, 1888, p. 523, fig. 2.)

FIG. 54.—Rostellum of _G. moniliformis_. Greatly enlarged. (After Grassi & Calandruccio, 1888, p. 523, fig. 3.)

FIG. 55.—Hooks from same. Greatly enlarged. (After Grassi & Calandruccio, 1888, p. 523, fig. 4.)

FIG. 56.—Eggs of _G. moniliformis_, with embryo. Greatly enlarged. (After Grassi & Calandruccio, 1888, p. 523, fig. 5.)

FIG. 57.—Egg very greatly enlarged. (After Grassi & Calandruccio, 1888, p. 524, fig. 6.)

FIG. 58.—A young larva of _G. moniliformis_ in a _Blaps_; the rostellum is invaginated and the larva is surrounded by a thick inner jelly-like and thin outer cuticular covering. Enlarged. (After Grassi & Calandruccio, 1888, p. 524, fig. 7.) ]

ARACHNOIDEA.

Genus LINGUATULA Frœhlich, 1789.—Tongue worms.

Species LINGUATULA SERRATA Frœhlich, 1789.

The larva of this parasite is found encysted in the entrails of rabbits, cattle, and certain other animals, and it becomes mature in the nasal cavities of canines.

Both the larva and the adult have been reported for man, and the larva has been reported as occurring in _Mus decumanus_.

As canines are not fond of eating rats, the presence of the larval tongue worm in the latter is of more academic interest than practical importance, and although the theoretical possibility must be admitted that a dog by eating rats might become infected with tongue worms and eventually might transmit the infection to man, these possibilities seem somewhat remote. Remote possibilities must also be admitted to the effect that if a person ate a rat infected with tongue worms this person might become infected.

COMPENDIUM OF ANIMAL PARASITES REPORTED FOR RATS AND MICE (GENUS MUS).

By CH. WARDELL STILES, Ph. D., _Public Health and Marine-Hospital Service_,

and

ALBERT HASSALL, M. R. C. V. S., _Assistant, Division of Zoology, United States Bureau of Animal Industry_.

The following list of parasites is prepared from the detailed host catalogues of the zoological divisions of the Public Health and Marine-Hospital Service and the Bureau of Animal Industry.

The species of hosts and parasites are taken as given by the various authors. It is needless to say that no list of this kind can ever lay claim to being complete.

Genus MUS Linneaus, 1758.

[_Mus musculus_ should be the type species.]

MUS AGRARIUS.—Harvest Mouse.

CESTODA:

_murina_ Dujardin: Hymenolepis.—Small intestine. [See fraterna.]

NEMATODA:

_obvelata_: Oxyuris.—Intestine.

ARACHNOIDEA:

_acuminatus_ Neumann: Ixodes.—External.

INSECTA:

_fasciatus_ Bosc: Ceratophyllus.—External. _musculi_ Dugès: Ctenopsyllus, Ctenopsylla.—External.

MUS ALBIPES.

INSECTA:

_pallidus_ Taschenberg: Pulex.—External.

MUS ALEXANDRINUS.—Roof Rat.

[See also _Mus rattus alexandrinus_.]

CESTODA:

_diminuta_ Rudolphi, 1819: Tænia, Hymenolepis.—Small intestine. _fasciolaris_ Rudolphi: Cysticercus.—Liver. _leptocephala_: Tænia.—Small intestine. _murina_ Dujardin: Hymenolepis.—Small intestine. [See fraterna.]

MUS ALEXANDRINUS ALBIVENTRIS.

CESTODA:

_diminuta_ Rudolphi: Hymenolepis.—Small intestine.

MUS AMPHIBIUS.

_Dubium_ Rudolphi.—Inguinal gland.

CESTODA:

_fasciolaris_ Rudolphi: Cysticercus.—Liver. _omphalodes_ Hermann: Tænia, Anoplocephala.—Intestine.

NEMATODA:

_nodosus_: Trichocephalus.—Cecum. _obvelata_: Ascaris.

MUS ARVALIS.

CESTODA:

_fasciolaris_ Rudolphi: Cysticercus.—Liver. _longicollis_: Cysticercus. _omphalodes_ Hermann: Tænia, Anoplocephala.—Intestine.

NEMATODA:

_nodosus_: Trichocephalus. _obvelata_: Ascaris.

ACANTHOCEPHALA:

_moniliformis_: Echinorhynchus.

MUS BARBARUS.

[See also _barbatus_ Enderl.]

INSECTA:

_spiculifer_ Gerv.: Hæmatopinus, Polyplax.—External.

MUS BRASILIENSIS Geoffr.

[See also _Holochilus brasiliensis_.]

CESTODA:

_pisiformis_ Zeder: Cysticercus.

NEMATODA:

_muris brasiliensis_ Diesing: Physaloptera. _obvelata_ Bremser: Oxyuris.

MUS CAPENSIS.

CESTODA:

_muris capensis_: Tænia.—Intestine.

NEMATODA:

_contortus_ Rudolphi: Trichocephalus.—Cecum.

MUS CRICETUS.

CESTODA:

_straminea_ Gœze: Tænia.—Intestine.

MUS DECUMANUS Pallas.—Brown or Norway Rat; German Wanderratte.

PROTOZOA:

? _balfouri_: Hæmogregarina.—Blood. _intestinalis_ Lambl, 1859: Lamblia.—Intestine. [See duodenalis.] _lewisi_ Saville-Kent: Herpetomonas, Trichomonas, Trypanosoma.—Blood. species Siebold: Sarcocystis.—Muscles.

TREMATODA:

_armata_: Cercaria. _muris_: Distomum. _spiculator_ Dujardin, 1845: Distoma, Echinostoma, Distomum, Echinostomum.—Small intestine.

CESTODA:

_brachydera_ Diesing: Tænia.—Small intestine. _contracta_ Janicki: Hymenolepis.—Intestine. _crassa_ Janicki: Hymenolepis.—Intestine. _diminuta_ Rudolphi: Tænia, Hymenolepis.—Small intestine. _fasciolaris_ Rudolphi: Cysticercus.—Liver. _horrida_ Linstow, 1901: Tænia, Hymenolepis.—Intestine. _microstoma_ Dujardin: Tænia, Hymenolepis.—Small intestine. _murina_ Dujardin, 1845: Tænia, Hymenolepis.—Small intestine. [See fraterna.] _nana_ Siebold: Hymenolepis.—Small intestine. [See fraterna, murina.] _pusilla_ Gœze: Tænia, Catenotænia.—Small intestine. _ratti_: Tænia.—Intestine. _relicta_ Zschokke, 1888: Tænia, Hymenolepis.—Small intestine. species Janicki: Hymenolepis. species: Hymenolepis.—Small intestine.

NEMATODA:

_annulosum_ Dujardin: Trichosoma, Trichosomum, Calodium.—Duodenum, small intestine. _anulosum_ see annulosum Dujardin: Trichosoma. _circumflexa_ Polonio: Trichina.—Encysted in peritoneum. _crassicauda_ Bellingham, 1840: Trichodes, Trichosoma.—Urinary bladder, ureter, kidneys, intestine. _hepaticum_ Bauer: Trichosoma.—Liver. _hepaticum_ Railliet, 1891: Trichosoma.—Liver. _hepaticus_ Bancroft: Trichocephalus.—Liver. _longus_ Grassi & Segrè: Strongyloides, Rhabdonema.—Intestine. _minimum_ Molin: Gongylonema. _murina_ Leuckart: Spiroptera.—Stomach. [See obtusa.] _muris_ Gmelin: Filaria.—Stomach. _obtusa_ Rudolphi: Filaria, Spiroptera.—Stomach. [See murina.] _obvelata_ Bremser: Oxyuris.—Large intestine. _papillosum_ Polonio: Trichosoma.—Urinary bladder. _rhytipleuritis_ Deslongchamps: Filaria.—Stomach. _schmidtii_ Linstow: Trichosoma.—Urinary bladder. species Davaine: Filaria [embryo].—Blood. species: Heterakis.—Large intestine. species undetermined: Oxyuris. species Gerstæcker: Spiroptera.—Encapsuled in wall of stomach and intestine. species Bakody: Spiroptera.—Encapsuled in walls of alimentary canal and muscles. species: Spiroptera.—Encapsuled in wall of stomach and intestine. species Parona: Strongyloides. species Lutz, 1894: Strongylus.—Small intestine. ? species Railliet: Trichosoma. _spiralis_ Owen, 1835: Trichina, Trichinella.—Adult in intestine, larva in muscles. _spumosa_ Schneider: Heterakis.—Cœcum and large intestine. ? _tenuissimum_ Leidy, 1891: Trichosomum.—Liver. [See hepaticum.]

ACANTHOCEPHALA:

_moniliformis_ Bremser: Echinorhynchus, Gigantorhynchus.

ARACHNOIDEA:

_agilis_ Koch: Lælaps.—External [See echidninus, musculi.] _alepis_ Railliet & Lucet, 1893: Sarcoptes, Notoedres.—External, ears, genitalia. _complanatus_ Kramer: Gamasus.—External. [See stabularis, fenilis.]

_decumani_ Tiraboschi: Myonyssus. _echidninus_ Berlese: Lælaps.—External. _ensifera_ Poppe: Myobia.—External. _fenilis_ Mègnin: Gamasus.—[See stabularis, complanatus.] _musculi_ Schrank: Pediculus, Myobia.—External, head. _musculi_ Mègnin: Hæmomyson.—External. [See echidninus, agilis.] _musculi_ Schrank: Myobia.—External. _ricinus_ Linné: Acarus, Ixodes.—External. [See rufus, sulcatus, sciuri.] _rufus_ Koch: Ixodes.—External. [See ricinus.] _sciuri_ Koch: Ixodes.—External. [See ricinus.] sp. n. Banks: Lælaps.—External. _stabularis_ Koch: Gamasus, Hypoaspis, Lælaps.—External. [See complanatus, fenilis.] _sulcatus_ Koch: Ixodes.—External. [See ricinus.] _tænioides_ Lamark (larva): Linguatula. [See serrata.]

INSECTA:

_acanthopus_ Denny: Hæmatopinus, Hoplopleura.—External. _bidentatiformis_ Wagner: Neopsylla.—External. _brasiliensis_ Baker: Pulex.—External. _canis_ Curtis: Ctenocephalus, Ceratophyllus.—External. _cheopis_ Roth.: Pulex, Læmopsylla.—External. _consimilis_ Wagner: Ceratophyllus.—External. _fasciatus_ Bosc: Pulex, Ceratophyllus. External. _felis_ Bouché: Ctenocephalus.—External. _irritans_ Linné: Pulex.—External. _lagomys_ Wagner: Ceratophyllus.—External. _londiniensis_ Roth.: Ceratophyllus.—External. _musculi_ Dugès: Ctenopsylla.—External. _mustelæ_ Wagner: Ceratophyllus.—External. _penicilliger_ Grube: Ceratophyllus.—External. _philippinensis_ Herzog: Pulex.—External. _serraticeps_ Gervais: Pulex.—External. _spinulosus_ Burmeister: Hæmatopinus, Polyplax.—External.

MUS DECUMANUS × MUS NORVEGICUS ALBUS.

PROTOZOA:

undetermined.—Small intestine.

CESTODA:

_fasciolaris_: Cysticercus.—Liver. species: Hymenolepis.—Intestine.

NEMATODA:

_spiralis_ Owen: Trichinella.—Artificial infection.

MUS DOMESTICUS = MUS MUSCULUS ALBUS.

ARACHNOIDEA:

_crotali_ Humboldt (larva): Porocephalus.—Encysted in various organs, experimental.

MUS FERCULINUS.

INSECTA:

_thomasi_ Rothschild: Stephanocircus.—External.

MUS FLAVIDUS.

CESTODA:

? _gracilis_ Janicki: Davainea.—Intestine.

MUS FULIGINOSUS.

ARACHNOIDEA:

_crotali_ Humboldt: Porocephalus.—Encysted in various organs.

MUS FURCIROSTRIS Wagner.

ACANTHOCEPHALA:

_moniliformis_ Bremser: Echinorhynchus.—Intestine.

MUS GENTILIS.

INSECTA:

_cheopis_ Rothschild: Pulex.—External.

MUS LEMMUS.

CESTODA:

_lemmi_: Tænia.—Intestine. [See muris lemmi.] _muris lemmi_: Tænia.—Intestine. [See lemmi.]

MUS MEYERI.

CESTODA:

_celebensis_ Janicki, 1902: Davainea.—Intestine.

MUS MINIMUS Ptrs.

NEMATODA:

species Linstow, 1901: Spiroptera.—Stomach.

MUS MINUTUS Pallas.—German Zwergmaus.

NEMATODA:

_obvelata_ Bremser: Oxyuris.—Cecum. _oxyura_ Nitzsch, 1821: Ascaris.—[See obvelata.]

MUS MUSCHENBROCKI.

CESTODA:

_polycalceola_ Janicki: Davainea.—Intestine.

MUS MUSCULUS[AC] Linné, 1758.—House Mouse.

Footnote AC:

In laboratory experiments the white mouse is used more than the ordinary form, but the host is frequently reported simply as “the mouse.”

——:

_Dubium_ Rudolphi, 1819.—Inguinal gland.

PROTOZOA:

_brucei_: Trypanosoma, Trypanozoon.—Blood, artificial infection. _dimorphon_: Trypanosoma, Trypanozoon.—Blood. _duttoni_ Thiroux, 1905: Trypanosoma, Trypanozoon.—Blood. _equinum_: Trypanosoma, Trypanozoon.—Blood, artificial infection. _equiperdum_: Trypanosoma, Trypanozoon.—Blood, artificial infection. _evansi_: Trypansoma, Trypanozoon.—Blood, artificial infection. _falciforme_ Schneider: Coccidium, Eimeria.—Intestine. flagellate, something like Herpetomonas bütschlii. _gambiense_: Trypanosoma, Trypanozoon.—Blood, artificial infection. _intestinalis_ Lambl, 1859: Lamblia, Megastoma.—Intestine. [See duodenalis, muris.] _muris_ Grassi: Amœba. _muris_ Bensen, 1908: Lamblia.—Intestine. [See intestinalis.] _muris_ Schuberg: Coccidium.—Intestine. _muris_ Smith & Johnson, 1902a: Klossiella.—Renal epithelium.

_muris_ Balfour: Leucocytozoon.—Blood. _muris_ R. Blanchard: Miescheria, Sarcocystis.—Striated muscle. _musculi_ Kendall: Trypanosoma.—Blood. _schubergi_ Labbé: Pfeifferella.—Intestine. species Th. Smith: Eimeria.—Kidney. species J. J. Clarke: Pfeifferella.—Intestine. species Miescher: Sarcocystis.—Muscles. _stercorea_ Cienkowski: Chlamydophrys.—Intestine.

TREMATODA:

_armata_: Cercaria. _muris_ Ercolani, 1882: Distomum. _musculi_ Rudolphi, 1819: Distoma, Distomum.—Intestine. _recurvum_ Dujardin, 1845: Distoma, Distomum.—Intestine.

CESTODA:

_canis lagopodis_ Viborg: Tænia.—Intestine. [See lineata.] _contracta_ Janicki: Hymenolepis.—Intestine. _crassa_ Janicki, 1904: Hymenolepis.—Intestine. _diminuta_ Rudolphi: Tænia, Hymenolepis.—Intestine. _echinococcus._ [See Devé, 1904, October 28; 264.] _fasciolaris_ Rudolphi, 1819: Cysticercus.—Liver. _imbricata_ Diesing: Tænia.—Small intestine. _leptocephala_ Creplin, 1849: Tænia.—Small intestine. _lineata_ Gœze: Tænia, Mesocestoides, Ptychophysa. [See canis lagopodis.] _microstoma_ Dujardin, 1845: Tænia.—Intestine. _murina_ Dujardin, 1845: Tænia, Hymenolepis.—Intestine. [See fraterna.] _muris capensis_: Tænia. _muris hepatica_ Rœderer, 1762: Fasciola.—Liver. [See fasciolaris.] _musculi_ Rudolphi, 1810: Tænia.—Abdominal cavity. _pisiformis_ Zeder: Cysticercus.—Liver. _pusilla_ Gœze, 1782: Tænia.—Intestine. species Janicki: Hymenolepis.—Intestine. species Merrem, 1781: Fasciola.—Liver. [See fasciolaris.] _tenella_ Pallas, 1781 pars: Tænia.—Abdominal cavity. [See musculi.] _umbonata_ Molin, 1858: Tænia.—Intestine.

NEMATODA:

_bacillatum_ Eberth: Trichosoma.—Esophagus. _hepaticum_ Railliet, 1889: Trichosoma.—Liver. _minimum_ Molin: Gongylonema.—On stomach, liver. _muris_ Gmelin: Filaria. _muris_ Werner: Lumbricus, Ascaris, Fusaria. [See obtusa Frœlich.] _muris musculi_ Creplin, 1849: Trichosoma.—Large intestine. _musculi_ Rudolphi: Filaria, Gongylonema.—Abdomen. _nodosus_ Rudolphi: Trichocephalus.—Intestine, cecum. _oxyura_ Nitzsch, 1821: Ascaris.—[See obvelata.] _obvelata_ Rudolphi: Oxyuris.—Cecum. _obtusa_ Rudolphi: Filaria, Spiroptera.—Stomach. _obtusa_ Frœlich, 1791: Ascaris.—Stomach. [See muris Werner.] _quadrialata_ Molin: Spiroptera.—Stomach. _semilanceolata_ Molin, 1858: Oxyuris.—Cecum. [See tetraptera.] _spiralis_ Owen, 1835: Trichina, Trichinella.—Adult in intestine, larva in muscles. _tetraptera_ Nitzsch: Oxyuris.—Cecum. [See semilanceolata.] _tricuspis_ Leuckart: Ollulanus.—Muscles.

ACANTHOCEPHALA: