294 Veterinary Medicine. 



of recurved hooklets, which arrangement gives the parasite its 

 name (echinos hook, thorn). The male is 2 to 3 inches long by 

 3 to 5 mm. thick, with caudal membraneous expansion around 

 the genital orifice. 'The female may be 7 to 11 inches long, 

 thicker than the male and with blunt caudal end. Ovum forms 

 an elongated ellipsis, and has three transparent coats through 

 which, in a few days after laying, the embryo can be seen as an 

 elongated cone with four hooklets on the cephalic end. 



Developm,ent and Metamorphosis . The ova, laid in the intes- 

 tine of the pig, escape with the faeces and are swallowed bj' the 

 larvse of the May beetle (Melolontha Vulgaris, Schneider), or by 

 gasteropod molluscs (Helix pomatia, H. hortensis, I,imax maxi- 

 mus, Ariou rufus) as in the experiments of I,espes. The latter 

 found embryos in the intestines of the molluscs and a developing 

 larva in the liver of Helix. Kaiser found that the egg was swal- 

 lowed by the rose cockchafer (Cetonia aurata), and the hatched 

 embryo bored its way from the stomach to the subcuticular 

 muscular layer in which it encysted itself. It seems probable 

 that the larval stage may be passed through in a variety of in- 

 vertebrates, which are in turn devoured by the pig and the larva 

 is set free to attain its mature development. 



Habitat of mature echinorhynchus . It has been found in the 

 small intestines of swiue with its protractile proboscis deeply 

 buried and fixed by its hooks on the mucous membrane, and its 

 caudal end floating distal from the stomach. They are not rare 

 in Germany, France, Austria, and America, and tend to abound 

 especially where hogs have a wide range and every facility for 

 feeding on invertebrates. 



Pathogenesis. The anchorage by the hooked proboscis of the 

 worm in the mucous membrane gives rise to the formation of 

 small congested papules on a white ground, with a central depres- 

 sion or sore in case the worm has let go its hold. The papules 

 may be the size of a hempseed or larger and are often complicat- 

 ed by minute abscesses scarcely larger. The perforations, usually 

 inconsiderable, will in exceptional cases, extend through the 

 mucosa, the muscles and even the serosa and give rise to infective 

 peritonitis. The mucosa may show numerous small cicatrices, 

 on a bluish gray ground. 



Symptoms. These are as with other intestinal worms : irregular 



