ASCARIS CANIS 



337 



are post-anal. The female measures 120 180 mm. in length ; the 

 posterior end is straight and somewhat conical ; the vulva is in the 

 middle of the anterior end of the body. The eggs are almost 

 spherical with a thin shell and an albuminous layer that is but 

 slightly protuberant. They measure 0*068 0-072 mm. 



Ascaris canis is a very common parasite in the intestine of 

 cats and dogs, but it also occurs in the lynx, lion, puma, &c. ; it 

 has also been observed in man in about eight cases, four in Eng- 



FIG. 219. Transverse section through the head part of 

 Ascaris canis from the cat, with the pterygoid prolongations 

 of the cuticle. In addition, one may note the four fields 

 of muscles, the longitudinal ridges with the oesophagus in 

 the transverse section (magnified). (After Leuckart.) 



FIG. 220. Ovum 

 of Ascaris canis, 

 with thin albu- 

 minous envelope 

 (magnified). 



land, two in Germany, one in Denmark and one in North America. 

 In two of these cases the parasites were coughed up. 



Grassi is of opinion that this species does riot occur in man, 

 as he vainly sought for it in over 1,000 persons, and experimental 

 infections on man yielded negative results. 



The development of Ascaris canis is similar to that of Ascaris lumbri- 

 coides ; but the eggs, in spite of the delicacy of their shells, have great powers 

 of resistance and develop equally well in water and damp earth, in a solution 

 of chromic acid, alcohol, turpentine, solution of soda, &c. It is, however, 

 but seldom that the embryos (0*36 mm. in length) hatch out. The trans- 

 mission is direct. 



LITERATURE. 



BELLINGHAM, O. B. Undescrib. Spec, of Human Intestinal Worm. (The Dublin 

 Med. Press, 1839, i., p. 104; Gaz. des hopitaux, 1839 [2], i., p. 97.) 



COBBOLD, T. Sp. On the occurr. of Asc. m. in the Human Body. (The Lancet, 1863, 

 i., p. 31.) 



MORTON, F. Asc. myst. (Ibid., 1865, i., p. 278.) 



LEUCKART, R. Menschl. Parasiten. (ist edit., ii., p. 261.) 



KELLY, H. A. (American Journ. of Med. Sc., 1884, [2] Ixxxviii., p. 483.) 



DAVAINE, C. Sur la const, de 1'oeuf des cert, entozoaires. (Mem. soc. biol., Paris, 

 1862 [3], iv., p. 273). 



HELLER, C. Ueb. Asc. lumbr. (Szgsber. d. Erlang. phys.-med. Societ, 1872, iv., p. 71). 



HERING. Beitr. z. Entw. einig. Eing.-Wurm. (Wiirttemb. nat. Jahreshfte, 1873, 

 p. 305.) 



GRASSI, B. Beitr. z. Kenntn. des Entwickelungscyclus von 5 Paras, d. Hundes 

 (C. f. B. u. P., 1888, iv., p. 609). 



GRASSI. B. Intorno all' Asc. myst. (Gazz. med. it. lomb., 1879, xxxix., p. 276.) 



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