82 DIRECT INJURIES CAUSED BY INSECTS. 



I call upon you to believe this ; 1 shall therefore leave you to act as you 

 please. — Thus much for pure Phthiriasis, which term ought to be con- 

 fined to maladies produced by lice. I shall only further observe, that as 

 many species as exist of these, which are the causes of disease, so many 

 kinds of Phthiriasis will there be.^ 



Acnri, or mites, are the next insect sources of disease in the human 

 species, and that not of one, but probably of many kinds, both loca 1 and 

 general. They are distinguished from Pediculi not only by their form, 

 but also often by their situation, since they frequently establish themselves 

 under the cuticle. With respect to local disorders, Dr. Adams conjectures 

 that Acari may be the cause of certain cases of Ophthalmia. Sir J. 

 Banks, in a letter to that gentleman, relates that some seamen belonging 

 to the Endeavour brig, being tormented with a severe itching round the 

 extremities of the eyelids, one of them was cured by an Otaheitan woman, 

 who with two small splinters of bamboo extracted from between the cilia 

 abundance of very minute lice, which were scarcely visible without a lens, 

 though their motion when laid on the thumb, was distinctly perceived. 

 These insects were probably synonymous with the Ciron des pnupieres of 

 Sauvages.^ — Le Jeune, a French physician quoted in MoufFet, describes a 

 case, in which what seems a different species, since he calls them rather 

 large, infested the white of the eye, exciting an intolerable itching.^ Dr. 

 Mead, from the Gervian Ephemerides, gives an account of a woman 

 suckling her child, from whose breast proceeded very minute vermicles.^ 

 These were probably mites, and perhaps that species, which, from its 

 feeding upon milk, Linne denominates Acarus Lactis. The great author 

 last mentioned describes an insect, a native of America, under the name 

 o( Pediculus Ricinoides, which, upon the authority of Rolander, he informs 

 us, gets into the feet of people as they walk, sucks their blood, oviposits^ 

 in them, and so occasions very dangerous ulcers. It would be an Acarus, 

 he observes, but it has only six legs. Now Hermann affirms, that some 

 species of Trombidium (a genus separated by Fabricius from Acarus) 

 have in no state more than six legs.^ Others of the tribe of Acarina, 

 and the insect in question amongst the rest, may be similarly circum- 

 stanced ; or those that Rolander examined might have been larvae, which 

 in this tribe are usually hexapods. 



Linne appears to have been of opinion that many conlageous diseases 

 are caused by mites.''' How far he was justified in this opinion I shall 

 not here inquire; facts alone can decide the question, and observations 

 made by men acquainted with Entomology as well as the science of dis- 

 eases. Considerable deference and attention, however, are certainly due 



' For further information oa this disease, see the valuable Manual of Entomology, by Dr. 

 Burmeister, for an English translation of which we are indebted to Mr. Shuckard (p. 3(J7.), 

 where, it is contended, but surety on inconclusive evidence, that Pedicuhis tahescentium, Alt. 

 {^Dissertatio de Phthiriasis, Bonnae, 1820) is produced by spontaneous generation. 



' On Morbid Poisons, 306, 307. 3 Mouffet, 267. 



* Mtdica Sacra, 104, 105. 



^ It is to be hoped this new word maybe admitted, as the laying of eggs cannot otherwise 

 be expressed without a periphrasis. For the same reason its substantive Oviposition will be 

 employed. 



^ Mem. Apterologique, 19. 



'' Insecta ejusmodi minutissima, forte, Acaros diversnc specie! causas esse diversorum 

 morborura contagiosornm, ab analogia et experientia hactenus acquisita, facili credimus 

 negotio. Ammn. Ac.Y.'^i. 



