GORDIACEA 



679 



and the egg-sacs, which open by means of oviducts into a uterus. The males 

 are often blackish brown, and the females light clay brown. 



The life-history of Parachordodes tolosanus is very complicated: the first 

 larva enters the larva of the alder-fly {Sialis lutaria L.), where it lives during 

 the winter, and passes over to the imago of the same insect, which is eaten by 

 a beetle [Pterostichus niger) . The first larva changes, becoming a second larva, 

 which lives in the beetle during the second winter, and finally escapes into the 

 water about twenty months after hatching. In the water it soon becomes 

 adult Gordiidae. 



The Gordiacea includes the family Gordiidae, which is divided by Camerano 

 into four genera: Gordius Linnaeus, 1758; Paragordius Camerano, 1879; Para- 

 chordodes Camerano, 1897; Chovdodes. 



Without going into details, it may be said that the following species have 

 been reported as parasitic in man : — 



Gordius aquaticus L., 1758. — Four recorded cases in Europe with abdominal 

 symptoms, pain, vomiting, etc., and nervous symptoms, hysteria, and neu- 

 ralgia. 



G. chiliensis E. Blanchard, 1849. — This is simply based on the legends of 

 Chilian Indians, who fear the worm. 



Paragordius varius Leidy, 1851. — Four cases of infection in North America. 

 Worms were expelled per anum or by vomiting. Symptoms: unimportant. 



P. tricuspidatus Dufour, 1828. — One case in France. Symptoms: slight 

 colic. Worm extracted from the throat. 



P. cinctus von Linstow, 1906. — From a man in Leydenburg in the Transvaal. 



Parachordodes tolosanus Dujardin, 1842. — ^Four cases, in one of which it is 

 accused of causing epileptiform fits. Cases occurred in France and Italy. 



P. pustulosus Baird, 1853. — One case in Italy caused anal pruritus and 

 discharge. 



P. violaceus Baird, 1853.— One case in France; it lodged in the throat 

 before expulsion. 



P. alpestris Villot, 1884.— One case in France. 



Undetermined. — Ward, in 1903, published the account of a case in which the 

 genus of the worm was not determined. 



CLASS II. 



ORDER III. ACANTHOCEPHALA Rudolphi. 



Nemathelminthes with a retractile proboscis armed with several rows of 

 spines or hooks; intestine absent; parasitic in the intestine of vertebrates. 



The Acanthocephala are elongated cylindrical worms, in which the body 

 can be divided into proboscis, neck, and trunk. The proboscis is a hollow, 

 finger-shaped, retractile process, covered with a thin cuticle, and armed with 

 rings of hooks arranged in longitudinal rows. The neck is not always dis- 

 cernible. The trunk has a rounded posterior end, and consists of a body-wall 

 with muscular layers, covered by a thin cuticle, enclosing the excretory and 

 reproductive organs. The sexes are separate. The male organs are two oval 

 testes, whose vasa efferentia unite into a vas deferens, which opens into a cirrus 

 contained in a pouch or bursa, and provided with a prostate gland. 



The female organs consist of two ovaries, which break down into masses of 

 cells which escape into the ccelom. Here the ova are fertilized and the embryo 

 is formed, and escapes through a funnel-shaped structure called ' the bell ' 

 into the uterus, and so through the vagina and the genital orifice at the 

 posterior end of the body into the lumen of the host's intestine. 



The embryo leaves the host with the faeces, and, getting into water, enters 

 the alimentary canal of a crustacean, water-insect, or fish, inside which it 

 hatches. It now bores its way through the intestinal wall into the coelom, 

 where it develops all its organs except the reproductive. 



The crustacean, water-insect, or fish must now be eaten by a vertebrate, 

 when the acanthocephalid becomes sexually mature in the intestine. They 

 are very rarely found in man. 



