70 



DIRECT INJURIES CAUSED BY IKSECTS. 



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 cir- 

 cumstanced ; or those that Holander examined might have 

 been larvae, which in this tribe are usually hexapods. 



Linne appears to have been of opinion that many contagious 

 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 diseases. Considerable 

 deference and attention, however, are certainly due to the 

 sentiments of so great a naturalist, in whom these necessary 

 qualifications were united in no common degree. With re- 

 spect to the dysentery and the itch, he affirms that this had 

 been manifested to his eyes. You will wish probably to know 

 the arguments that may be adduced in confirmation of this 

 opinion ; I will therefore endeavour to satisfy you as well as 

 I am able. The following history given by Linne seems to 

 prove the dysentery connected with these animals. 



Kolander, a student in Entomology, while he resided in 

 the house of the illustrious Swede, was attacked by the disease 

 in question, which quickly gave way to the usual remedies. 

 Eight days after it returned again, and was as before soon 

 removed. A third time, at the end of the same period, he was 

 seized with it. All the while he had been living like the rest 

 of the family, who had nevertheless escaped. This, of course, 

 occasioned no little inquiry into the cause of what had hap- 

 pened. Linne, aware that Bartholinus had attributed the 

 dysentery to insects, which he professed to have seen, recom- 

 mended it to his pupil to examine his faeces. Rolander, fol- 

 lowing this advice, discovered in them innumerable animal- 

 cules, which upon a close examination proved to be mites. It 



1 Mem. Apterologique, 19. 



2 Insecta ejusmodi minutissima, forte Acuros diversas speciei causas esse 

 diversorum morborum contagiosorum, ab analogia et experientia hactenus 

 acquisita, facili credimus negotio. Amcen. Ac. v. 94. 



