Injurious to Man. 



21 



says that mites of this genus often make their appearance in cases 

 of sores of long standing, ulcers, etc., especially in lepers, but do 

 not convey the disease. 



One or more species of Tyroglyphus are occasionally found in 

 vanilla, and are said to set up a skin-complaint called " Vanillisme " 

 in persons coming in contact with this substance. 



Rhizoglyphus parasiticus, Dalgetty, is stated by that author to 

 be the causative agent of a superficial vesicular dermatitis known 

 under the name " Water Itch," occurring during the wet seasons 

 of the year amongst coolies employed in tea-gardens in Assam. 

 Coolies who are already in 

 a state of ill-health are the 

 persons chiefly affected by this 

 disease, and it only attacks 

 the feet. The disease does not 

 appear in tea-plantations until 

 they are several years old and 

 have become thoroughly con- 

 taminated with human ex- 

 crement and other refuse. 

 According to Dalgetty, both 

 ova and mites are found in 

 the pustules characteristic of 

 the disease. The best means 

 of preventing this disease is 

 for the coolies to wear shoes. 

 It should be noted that the 

 European species of Rhizo- 

 glyphus are vegetable feeders, 

 attacking bulbs, the roots of 

 plants, etc. 



In 1864 Bogdanoff described and figured a mite under the 

 name Dermatophagoides scheremctcivskyi. He says that this 

 Acarus was found by Scheremetewsky more than twenty times on 

 the skin of persons suffering from itch at Moscow. In his well- 

 known treatise on Medical and Agricultural Zoology, Eailliet 

 regards this mite as being the same as Chorioptes bovis, Gerl, but 

 it is more probable that it is a Tyroglyphid mite. 



According to Brumpt, Ludwig found numerous specimens of 

 Histiogaster cntomopliagus, Laboulbene, in a digital tumour. 



Specimens of a Tyroglyphid mite were also discovered by 

 Moriggia, in 1866, in a large horny growth on the hand of an old 



Fig. 9. 



House-mite, GlycypJiag as domesticus, 

 X 50. (After Michael.) 



