S'6 DIRECT INJURIES CAUSED BY INSECTS. 



If these observations be allowed their due weight, it 

 will follow, that a disease produced by animals residing 

 under the cuticle cannot be a true Phthiriasis, and there- 

 fore the death of the poet Alcman, and of Pherecydes 

 Syrius the philosopher, mentioned by Aristotle, must 

 have been occasioned by some other kind of insect. For, 

 speaking of the lice to which he attributes these cata- 

 strophes, he says that " they are produced in the flesh in 

 small pustule-like tumours, which have no pus, and from 

 which, when punctured, they issue 3 ." For the same 

 reason, the disorder which Dr. Heberden has described 

 in his Commentaries, from the communications of Sir E. 

 Wilmot, under the name of Morbus pedicularis, must 

 also be a different disease, since, with Aristotle, he like- 

 wise represents the insects as inhabiting tumours, from 

 which they may be extracted when opened by a needle. 

 He says, indeed, that in every respect they resemble the 

 common lice, except in being whiter ; but medical men, 

 who were not at the same time entomologists, might ea- 

 sily mistake an Acarus for a Pediculus b . 



Dr. Willan, in one case of Prurigo senilis, observed a 

 number of small insects on the patient's skin and linen. 

 They were quick in their motion, and so minute that it 

 required some attention to discover them. He took them 

 at first for small Pediculi ; but under a lens they appeared 

 to him rather to be a nondescript species of Pulex c ; yet 

 the figure he gives has not the slightest likeness to the 



a Hist. Animal. 1. 5. c. 31. 



b From the terms employed by Aristotle and Dr. Mead in their 

 Account of these cases, it appears that the animal they meant could 

 not be maggots, but something bearing a more general resemblance 

 to lice. 



c On Cutaneous Diseases, 87, 88; and t. 7-f. 4. 



