ARTHROPODA 555 



Blanehard recently called the attention of physicians to the occurrence of 

 some varieties of gordius— small, elongated, thin worms having the shape of 

 filariae— as occasional parasites of man. He spoke particularly of the gordius 

 aquaticus, gordius argillaceus and gordius medinensis, which live in fresh 

 water, notably in the springs of mountainous regions. They are introduced 

 into the human intestinal tract by drinking-water, as well as by the ingestion 

 of fruit, and are finally voided. In all about seven transmissions have been 

 observed. 



Almost as rare in man is the occurrence of the acanthocephala, a nematode- 

 like parasite without intestines whose anterior end is armed with a proboscis. 

 The echinorhynchus gigas, Goeze, 1782, is found in great numbers in the 

 small intestine of swine. According to Leuckart its presence in man has been 

 proven in a few cases. Lambl once observed the echinorhyncus hominis. It 

 has been shown by artificial infection experiments that echinorhyncus monili- 

 formis, Bremser, 1819, may occur in man. 



Hirudines have been observed as occasional parasites of man, and may be 

 transmitted to man. Even now they are frequently used for medicinal pur- 

 poses. Among them have been noticed: Hirudo medicinalis, Linne, 1758, 

 Hirudo troctina, Johnston, 1816, Hirudo ceylonica BL, Limnatis nilotica, 

 Savigny, 1820. These are found upon the skin or in the oral cavity of man, 

 and soon begin their blood-sucking activity. 



ARTHROPODA 



The arthropoda, particularly the arachnoids, the spiders and the insects, 

 are found in great numbers as, parasites of man. Owing to their manner of 

 life they appear chiefly as ectoparasites. To these belong the 



Leptus autumnalis, Bliaw, 1790. 



The so-called gooseberry or harvest acarus, which is 0.3-0.5 mm. long, 

 and of a reddish color, lives in great numbers through the summer in immature 

 forms on grass and shrubs, and occasionally as parasites upon man and other 

 mammals. The ova of the trombidium holosericum, which are conspicuous 

 in many gardens by their red color, are deposited in June or July. From these 

 a larva develops which we recognize as the leptus autumnalis. This larva bores 

 into the skin with its head and produces a severe cutaneous inflammation with 

 itching which may be relieved by washing with soap, by inunctions with bal- 

 sam of Peru, or 5 per cent, of carbolic solution or benzine. 



Similar varieties of acarus such as tetranychus molestissimus, Weyen- 

 bergh, 1886, pediculoides ventricosus, Newport, 1850, tarsonemus intectus, 

 Karpelles, 1885, pygmephorus uncinatus, Flemming, 1884, have been found in 

 workmen who had handled Indian, Bulgarian or Eussian grain, and suffered 

 from an itching skin eruption. Other varieties of acarus cheyletus eruditus 

 (Schrank, 1781), and tj^deus molestus (Monig) which are found in rags, 

 stables, and tobacco stores, also attack man and give rise to distressing itching. 



The dermanyssus avium (Duges, 1834), the bird acarus, is better known. 

 It occurs in chickens, pigeons and in our song birds when kept in cages; it 



