Q4 DIRECT INJURIES CAUSED BY INSECTS. 



warmth upon them in exciting motion.^ Our intelligent countryman also 

 observes that they cannot be Pediculi, since they live under the cuticle, 

 which lice never do.^ In the epistle dedicatory, the editor speaks also of 

 them as living in burrows which they have excavated in the skin near a 

 lake of water ; from which, if they be extracted with a needle and put 

 upon the nail, they shew in the sun their red head and the feet with which 

 they walk."' And to close my veteran authorities, Junius thus explains 

 the word Acarus, as I find him quoted in Gouldraan's useful dictionary, 

 "A small worm, which eats under the skin, and makes burrows in itching 

 hands."^ 



In more modern times, microscopical figures have been added to descrip- 

 tions of the insect. Bonomo first furnished this valuable species of elu- 

 cidation. His figures, however, which are copied by Baker in his work 

 on the microscope, are far from accurate.^ Those of De Geer and Dr. 

 Adams are much more satisfactory, and mutually confirm each olher.^ 

 From them it is evident that the same insect inhabits the scabies of Sweden 

 and Madeira. Dr. Bateman, in the letter before alluded to, informs his 

 correspondent, that he had seen that from Madeira, and gives it as his 

 opinion, that there cannot be a doubt of the existence of an Acarus 

 Scabiei; an opinion which he repeats in his late work on Cutaneous 

 Diseases, and which, according to Hermann'', has been also rendered 

 unquestionable by Wichmann in his Etiohgie de la Gale (Hanovre, 1786), 

 a work I have not had an opportunity of consulting. From all this we 

 may regard the point as so far settled, that an animal of this kind exists 

 at least as an occasional concomitant of scabies. 



Tliis fact being ascertained, a more complex inquiry remains, which 

 branches out into two distinct questions. Is scabies always produced by 

 these insects ? Or, if this be not the case, is the animate scabies a distinct 

 disease from the inanimate ? 



It is very remarkable that Linne, a physician as well as a naturalist, 

 and De Geer, one of the most accurate observers that ever existed, should 

 both assign the insect in question as the undoubted cause of the common 

 scabies of their country ; the one applying to the disease he was speaking 

 of the epithet of communissima, and observing the fact to be notorious 

 (cuique liquet), and the other designating it by its well known French 

 name. La Gale.^ And is it not equally remarkable that such men as John 

 Hunter, Dr. Heberden, Dr. Bateman, Dr. Adams, and Mr. Baker, should 



1 Extractus acu et super ungue positus, movet se si solis etiam calore adjuvetur. ubiswpr, 

 Ungui imposilus vix movelur : si vero oris calido halitu affletur, agilis ia ungue cursitat. 

 Fn. Suec. 1975. 



* Neque Syrones isti sunt de pediculorum genere, ut Johannes Langius ex Aristotele 

 videtur asserere : nam illi extra cutera vivunt, hi vero non. ubi supr. 



3 Imo ipsi Acari prse exiguitate indivisibiles, ex cuniculis prope aquae lacum quos fode- 

 runi in cute, acu extracli et ungue impositi, caput rubrum, et pedes quibus gradiuntur ad 

 solem produnt. p. vi. 



* Teredo sive exiguus vermiculus, qui subter culem credit agitque cuniculos in prurigi- 

 nosis manibus. Gouldman tells us these Acari were also called Hand-worms, Another 

 English name ts given in Mouffet, viz. Wheale-rvorms. 



5 Osservazioni intorno a pelliceUi del corpo umano fatte dal Dottor Gio Cosimo Bonomo, &c. 

 /. 1—3. Baker, On Microsc. i. t. 13. f. 2. 



« De Geer, vii. t. 5.f. 12. 14. ' M6m. Apterohgiqrie, 79. 



* I am informed by my learned friend Alexander MacLeay, Esq. late secretary to the 

 Linnean Society, that, in the north of Scotland, the insect of the itch is well known, and 

 easily discovered and extracted. 



