EXAMINATION OF CYSTICERCOID STAGES 165 



intestine, as Strongylus contortus, Eud., in the abomasum of sheep and 

 cattle ; 8. ostertagi, Stiles, under the epithelium of the abomasum 

 of cattle ; Sclerostomum armatum, (Kud.), and allied species, sexually 

 mature in the intestine of horses, as larvae in the arteries of the 

 abdomen, where they give rise to verminous aneurism; Ankylostoma 

 trigonocephalum in dogs ; and other varieties. Other Strongylidae in- 

 habit the lungs, as : S. rufescens, Lkt. ; S. filaria, Eud., in sheep ; 

 S. apri, Gm., in swine; and other varieties. With the exception 

 of Trichinella, the Trichotrachelidae are represented by : Trichocephalus 

 crenatus, Eud., in swine; T. affinis, Eud., in the sheep, goat and ox; T. 

 depressiusculus, Eud., in the dog. Examples of the Filariae are pro- 

 vided by Filaria equina, Abild., in the body-cavity of the horse ; 

 *F. immitis, Leidy, in the heart of the dog ; and other varieties. Gnatlio- 

 stoma hispidum, Fedtsch, is found in the stomach of swine of 

 Hungarian origin ; the male of this species is up to 25 mm. long, 

 while the female may attain a length of 31 mm. 



(4) ACANTHOCEPHALA (HOOKED WORMS). 



The Acanthocephala are found in the intestine of vertebrates. 

 The smaller species have considerable transparency and are well 

 suited to a first examination, the details of their structure being 

 clearly visible with a low power lens if they are pressed between two 

 glass slides. Material will be found in the intestine of frogs and of 

 fresh and salt-water fish. The parasites are furnished with an armed 

 cylindrical proboscis, by means of which they attach themselves to 

 the bowel-wall ; they are, however, easily detached. The trunk is of 

 a white or reddish-yellow colour, and, in the living specimen, is usually 

 quite flat with irregular transverse wrinkles. When put into water 

 or other liquid it swells up and becomes cylindrical, but does not lose 

 its transparency. As soon as the worm is removed from the host, it 

 should be put on to a cover-glass with a little normal saline and 

 examined. If the proboscis is withdrawn, the worm should be 

 squeezed with the fingers, the pressure being directed from the thin 

 posterior end forwards, and this manoeuvre should be repeated until 

 the proboscis appears. A cover-glass should then immediately be 

 placed upon the worm, and if this is insufficient to prevent the 

 reinvagination of the proboscis, the pressure should be increased. 



The Acanthocephala are, without exception, dioecious. The sexes 

 are distinguished in the first place by difference in size, the male being 

 considerably shorter than the female. The anterior end of both is 

 somewhat thickened and is crowned with a rostellum, which 

 may be cylindrical, ball, or club-shaped, according to species, but is 

 invariably furnished with rings of hooks. The number, shape and 



