50 DIRECT INJURIES CAUSED BY INSECTS. 



But besides these Acanne diseases, there seems to be one (unless with 

 Linne we regard the plague as of this class 1 ) more fearful and fatal than 

 them all. You will, perhaps, conjecture I am speaking of that described 

 by Aristotle and Sir E. Wilmot as the Pkthiriasis, and your conjecture 

 will be right. But some think, and those men of merited celebrity, that 

 mites have nothing to do in these and similar cases, for that maggots 

 were the parasites mistaken for lice. This, from the passage above 

 quoted, appears to have been Dr. Willan's opinion, to which, in the letter 

 so often referred to, Dr. Bateman subscribes, adding as a reason for ex- 

 cluding mites from being concewed, that " they are too minute, and 

 never have been seen in such numbers as to be mistaken for lice." But 

 both vary in size, some of the former being larger than some of the latter. 

 And allowing them to be ever so minute, yet when they issue in swarms, 

 as mites from a cheese, they would be very visible, were it only from 

 their motion. Besides, as they are furnished with legs, their motions 

 resemble those of lice infinitely more than do the contortions of maggots. 

 So that a mite would be deemed a louse much sooner by an unentomo- 

 logical observer than would a maggot. Whether mites have ever been 

 seen in such numbers as to be mistaken for lice, is the point in question, 

 and therefore, by itself, cannot be admitted for a valid argument. Though 

 Acarus Scabiei does not appear to swarm in ordinary cases, yet this is 

 certainly no reason why other species may not do so. Where it has 

 once made a settlement, how incredibly, and in how short a space of time, 

 does the Siro or cheese-mite multiply ! Acarus destructor and many other 

 species are equally rapid in their increase. Millions of lice are said by 

 Lafontaine, whom Hermann calls a very exact describer, to show themselves 

 in Plica polonica, on the third day of the disease 2 ; but whether the last- 

 mentioned author be correct in thinking it more probable that they are 

 mites 3 , I have not the means of judging. 



I shall now produce two instances where mites were evidently con- 

 cerned. Dr. Mead, from the German Ephemerides, relates the miserable 

 case of a French nobleman, from whose eyes, nostrils, mouth, and urinary 

 passage, animalcules of a red colour, and excessively minute, broke forth 

 day and night, attended by the most horrible and excruciating pains, and 

 at length occasioned his death. The account further says, that they 

 were produced from his corrupted blood. This was probably a fancy 

 originating in their red colour; but the whole history, whether we con- 

 sider the size and colour of the animals, or the places from which they 

 issue, is inapplicable to larvce or maggots, and agrees very well with 

 mites, some of which, particularly Leptus autumnatis y are of a bright red 

 colour. The other case, and a very similar one, is that recorded by 

 Mouffet of Lady Penruddock, concerning whom he expressly tells us, 

 that Acari swarmed in every part of her body her head, eyes, nose, lips, 

 gums, the soles of her feet, &c., tormenting her day and night, till, in spite 

 of every remedy, all the flesh of her body being consumed, she was at 

 length relieved by death from this terrible state of suffering. Mouffet 

 attributes her disease to the Acarus Scabiei, but from the symptoms and 



history of this parasite in his report in the Nouv. Ann. du Mus. iv. 213. See also 

 Raspail's Memoire Comparatif sur VHist. Nat. de VInsecte de la Gale. 



1 Amcen. Ac. ubi supr. 101. 



2 Traites de Chirurgie, &c. Leipsig, 1792. 3 j/<? w . Apterolog. 78. 



